Gran Turismo 2 Modding Ideas:Racing modifications

[Luis_Emilio]

Hey guys today we will make some ideas for editing racing modifications of the stock cars of gran turismo 2
Let's start

1.We can change the honda accord 1996 (Castrol mugen accord racing modification) to this one
(Jaccs Accord)

NOW.

2.We can change The Lancia Stratos Racing Livery. To this one (Martini Rally Car)

3.We can make the Lotus Elise (Model what you want Recommended 190) racing modification to look like this (Just a random Gulf Lotus Elise)

 

[GTvsForza]

I should make those in Forza

 

[Luis_Emilio]

I should make those in Forza

So. Go to make them AND ROCK!!
@MMRivit I think you can edit liveries without mip mapping errors....

 

[F40LM]

Can you make the Ford Escort Rally car in one colour please, Red if its not too much trouble

 

[michael_s_k]

Well I am clearly joining this surprisingly small but very cool modding ideas party rather late, but I appreciate the poster's theme and humorous images + comments. I do have a few racing modification ideas for interesting/amusing vehicles but must confess that I have a more serious/academic GT 2 challenge that's rather dampening my normally good GT 2 cheer so in the hope of increasing my understanding & diminishing or making extinct my current tuning annoyance, I intend to post a specific GT 2 racing modification question (see below) here which I'll preface with my general understanding of what GT 2 racing modifications do. In my experience and in considering the many reports of other Gt 2 players, racing modification in GT 2 normally includes the following:

1. Lighten the vehicle's weight, sometimes more, sometimes less depending on the weight of the car in question.
2. Change the exterior color(s) and graphical composition to sometimes compelling but also occasionally not-so-aesthetically-appealing factory designs (players sometimes have a choice in terms of colors and styles), and these exterior changes may include adding decals, car numbers or empty car number squares, sponsor logos and so on.
3. Add full customization transmission & suspension, changing several component settings to "racing" and allowing the modification of down-force. I have noted racing modification also sometimes add titanium exhausts tips and other cosmetic and even aero components which can alter a car's exterior appearance and, potentially, performance.

More recently as I have finally taken the time to more comprehensively study the finer points re: modification and tuning especially in areas where my understanding was poor, I have heard about, read about, and now apparently experienced for myself, racing modifications causing significant changes to RPM, torque levels and on a related note, transmission settings. Which brings us at last to my question or at least my desire for some corroboration, validation he he, and understanding through replies from other Gt 2 enthusiasts who've shared this experience: racing modification substantially (and sadly, permanently) altering a vehicle's transmission settings all too frequently for the worse.

So: Has the racing modification alteration-of-transmission settings phenomenon occurred to any of you, my fellow GT 2 enthusiasts? If so, please chime in and let me know including any details you find interesting, important, humorous or otherwise salient. Thank you!

- Michael

 

[submaniac93]

- 3. Add full customization transmission & suspension, changing several component settings to "racing" and allowing the modification of down-force. I have noted racing modification also sometimes add titanium exhausts tips and other cosmetic and even aero components which can alter a car's exterior appearance and, potentially, performance.
- racing modification substantially (and sadly, permanently) altering a vehicle's transmission settings all too frequently for the worse.

No it doesn't. Racing modification only alters the body of a car, which only includes the weight reduction multiplier to be applied to the car (in %), a body roll reduction muliplier (in %), drag coefficient, front minimum/maximum/default and rear mini/maxi/default downforce settings, 2 currently unknown values, and a width value that's used to display the body's width in the specs sheet.

It does nohing else.
You can install a RM to a car you just bought, and it will just become a racing-like plain stock vehicle, that's it.
Any claim that installing the RM caused all those changes is either the result of data corruption, or a misundersanding, or a straight up hoax.

 

[michael_s_k]

Thanks for your reply. I agree that data corruption could well be the culprit.

Unless I misinterpret your words and the ideas behind them, you do write in your response as though I've no prior experience with RM in GT 2 and further subtly suggest that I am intentionally making baseless claims, casually opening the door leading to the butterfly-soft suggestion that some or all of what I've reported is false, assertions which are unnecessary and seemingly of a schadenfreude nature.

As you may have noted, I have only experienced this post-RM gearing change with one car and found it very strange as I had never experienced a racing modification changing gear ratios in the past and I've performed many. And the only unusual change I personally experienced was the alteration of my gear ratios for each level of the customization auto-tune. So, I was not reporting "all those changes" as 1st-person experiences, many were second-hand.

My primary concern was with the possibility of racing modification effecting the transmission which, as I've said, is not to the best of my knowledge and experience part of the RM process. Reading in various GT forums I have noted several player reports describing odd transmission-related changes along with some unusual cosmetic changes as well. I do realize, as you stated, making it rigidly and icily salient, that such reports might be the result of data corruption, a misunderstanding, or a hoax but the changes I experienced were although quite unusual nonetheless completely accurate and representational of an actual in-game experience that I spent several hours investigating, hoping to determine the ultimate truth of the matter.

And based on my personal experience, data corruption or not, racing modification absolutely did result in the vehicle in question ending up with the completely unheard-of result: changes to the gear ratio settings. I am about to replicate the process to determine whether or not the bizarre gear ratio changes occur again. I anticipate that it was just a glitch and that no changes will occur beyond the modest and expected "normal" RM results.

But, if it does reoccur than it suggests that in some rare instances RM does, as a few other GT players have reported, result in changes beyond the weight reduction, color/design changes, settings changed to "racing", addition of all tire along with modifiable suspension and transmission which everyone already had anyway lol and w/some cars aero parts being added.

In addition to the above-mentioned changes, some GT players have written of further unexpected RM changes including titanium exhaust tips and some other cosmetic alterations to the interior (in versions above GT 2) and exterior beyond what we normally see, but I have not bothered to follow-up on this as, again, I was most curious regarding the possibility that RM played a hand in my case, causing changes well beyond the norm. I am working for now from the reasonable idea that data corruption played a hand here and am about to test the entire RM process utilizing both the same make/model/year vehicle as the one originally displaying subtle but salient changes to the transmission settings post-RM and at least two other equivalent make/model/year vehicles to check for any unexpected post-RM results. Again, I anticipate it was all a one-time-deal caused by a read/write or other error but having experienced such an unusual RM result, I feel compelled to thoroughly test the hypothesis that racing modification always produces the same set of results, and while I am certain it does and willing to chalk my experience up to a mere data error, I am interested most of all in simply increasing my understanding of the game including determining empirically the absolute facts re: racing modification.

In short, I agree re: the expected racing modification results, and having experienced results far from mundane I will perform experiments determining if the highly unusual RM gear ratio changes I experienced were indeed the result of a mere data error or if there are instances during which a RM will make unusual changes to the transmission and/or anything else not via a random misread or write of data values but rather, by design. That'd definitely make things more interesting but I am hoping for the simpler same-outcome-every time one performs a racing modification result.

Thanks again for your reply.

PS - When I wrote that I'd "seen" titanium exhaust tips, in retrospect I am not totally certain that's the case. I had recently read a GT 2 post in which a third party reported noting titanium exhaust tips on some cars that had undergone racing modification and it sparked a vague recollection of having witnessed this myself but looking back on, I am just not absolutely certain. But I will be keeping an eye out for just in case. Again, I am in agreement with the consensus regarding the results of a racing transmission, but my recent gear ratio alterations post-RM definitely gave me pause so I hope that the four simple experiments I am about to perform will answer my question once and for all.

 

[michael_s_k]

submaniac93 -​

Ok, I performed the following test, first using two 96 Supra RZs (mistakenly listed as 97 Supra (Turbo) in-game), then two 97 Supra RZs :​

As noted previously, after RM-ing the first car, one of the two 96 Supra RZs, I noticed that for many of the auto-set gear ratios (not setting one but definitely settings 11-22, all ratios had increased with the racing modification. I then RM the non RM 96 Supra RZ and after race modification its gear ratios had likewise increased to match the first racing modified 96 Supra RZ.

I repeated this process with the two 97 Toyota Supra RZs. Neither started out as RM and their gear ratios were identical through all auto-sets. I race modified 97 Supra #1 and afterward its gear ratios had increased above the non RM 97 Supra RZ. I then racing modified 97 Supra RZ #2 and its gear ratios had increased to match racing modified Supra RZ #1.

My next step is to try this experiment with a variety of vehicles of other (matching) makes/models/years to determine if this gear ratio alteration during racing modification occurs with all vehicles or just some specific cars. For example, I may compare the gear ratios of a RM 99 Nissan Skyline R34 against the gearing for a non RM 99 Nissan Skyline R34 both of the same exact model type and do the same with some other identical makes/models/year and see if there continue to be differences. I will continue to modify using newly-purchased vehicles equipped and tuned identically and perform the same test also using pre-existing vehicles as possible.

At this point I am surprised and curious as to whether this is specific to individual model years and even series of cars (like the Toyota Supra RZs), if it occurs to all RM cars or if my Gran Turismo game is somehow compromised. For years I just took it for granted that racing modification did not change gear ratios but a series of events led me to notice a contrary difference in top speeds between RM versions of a given vehicle and non RM versions which led me to dig into all the settings and eventually I noticed the altered gear ratios post-RM.

It's easy to dismiss all of this as nonsense, but try comparing the differences in the auto-set gear ratios between the R model of a given make/model/year vehicle against its non-RM twin and see for yourself. If you do so with the 97 rzs and they both have identical gear ratios in sets like 18-22 especially I will be lead to believe that my GT 2 is compromised somehow. Again, I have only performed this test using two 96 Supra RZs and two 97 Supra RZs so perhaps this effect applies only to specific vehicles or vehicle lines. I'll test that next. In the meantime, just wanted to report what I have discovered so far.

 

[michael_s_k]

@submaniac93 -​

Ok, performed the same RM vs non-RM pre-set gear ratios check using Tommy K ZZ-S coupes and once again the RM model had gear ratios automatically set slightly higher after RM than the non RM ZZ. So, is it just my Gran Turismo emulator or is this an actual thing? Appreciate your feedback.

 

[submaniac93]

Unless I misinterpret your words and the ideas behind them, you do write in your response as though I've no prior experience with RM in GT 2 and further subtly suggest that I am intentionally making baseless claims, casually opening the door leading to the butterfly-soft suggestion that some or all of what I've reported is false, assertions which are unnecessary and seemingly of a schadenfreude nature.

Sorry, i didn't mean nor intended to sound that way, i was just stating that if it had been something you'd heard of, it could've been a baseless rumour.

Everything else i've listed is what makes up the upgrade that is a racing modification. As in, i've access to the actual files the game loads from what me and others have found over the years of reverse engineering GT2.
And with the way the upgrades work in GT2, the RM upgrade itself has nothing that suggests it affects aything else than the weight of the car and the downforce values, physics-wise.
This here is the data that makes up the RM of the 1996 Supra RZ, in its entirety.

GT1 and GT2's racing modifications are not to be confused with GT5's version of it. In GT5, it's an entirely different car, with its own specs, parts, and settings, swapped in place of your previous car.
In GT1 and GT2, it's purely a cosmetic change, a toogle on the downforce settings becoming modifiable, and a "stage 4" weight reduction upgrade (although it isn't, hence the quotes)

I've just tried your expriement on my end and I can't reproduce the change. I bought 2 '96 Supra RZ, RMed one of them and checked their gears, they're identical (3827, 2360, 1685, 1312, 1000, 0793, f3266), as they should be, because i haven't bought the Full race transmission part.
After buying an other set of 96RZs, i first bought the racigg transmission, then I RMed one of them, and both have the same gear ratios of 3202, 2214, 1643, 1276, 1037, 0882, 3266 at the default auto level 10, which again, makes sense as those ratios are calculated taking the car's maximum engine RPMs and the auto setting's target speed value. Both of which the RM part doesn't affect.
For the sake of trying to match what you've told me above, i've set the gear ratios of both cars to auto level 17 and both have the same ratios of: 2884, 1912, 1383, 1050, 0837, 0700, f3266

However, i can tell you what parts can/will (and could for some) affect your car's gear ratios when you equip the racing transmission after buying/equipping said parts, because they have the ability to affect a car's maximum revs:
ROM, Engine Balance, Port/Polish, Displacement Increase all have the ability to add/remove RPMs to the engine. In fact, data-wise, they all are identical in what they can do. However, only Engine Balance was ever set to affect a car's RPMs (EB adds 100RPMs to all cars) by the developers.
Here's their data for the Supra 96RZ (note: I used the Skyline R34 V-spec's Displacement Increase upgrade as the Supra does't have any)

Turbo Kits can also affect RPMs, but it's an other part genre whhere that feature was never used. (Supra 96RZ stage 4 Turbo here)

Naturally Aspirated Kits are the only major power upgrade to visibly alter a car's RPM values, as they add upwards of 1000rpm to most NA cars in the game, at least those that can equip a stage 3. Stage 1 and 2 add just a few hundred RPMs to an engine's redline and maximum revs.
Shown here is the Stage 3 NA Tune from the 1996 Supra SZ-R, +500RPMs in this case.

These all technically speaking have the "power" to affect a car's gear ratios, provided the gear upgrades are installed after the power upgrade. After is important, because the game recalculates auto gear ratios only when a transmission upgrade is applied to a car or you change the auto level/individual ratios.
If you buy a transmission upgrade before installing a power upgrade that alters RPMs, you'll notice that the gear ratios don't change.

As for the titanium exhaust tips, it's part of the visual upgrade because it's part of the 3D model of the RMed vehicle. It can also be part of the road model as well, it just depends of the texture applied to exhaust 3D mesh. And has zero consequence on the car's performance, such as drag coefficient etc. That'll be just a number in the body data.

I'm not trying to discredit you or anybody else, however, i'm providing facts backed by my own, and other people's research on how the internals of GT2 work.
Hence why i've mentioned that it's either some form of corruption, false rumour or misunderstandings.

However, you've now made me curious as to why this would happen to your game, as it's defintiely not (i believe i've given enough proof in this post here) intended game mechanics, and i'd love to have either a detailed description of what you do, what the steps you take are, from buying the car, to when you notice the gear ratios changing, if at all possible backed with a video recording or screenshots, because i'm genuinely curious as to why it would happen.

Sorry about the long post, you've unfortunately for better or worse attracted the attention of one of the most knowledgeable (to the point of being borderline obsessed i'll admit) GT2 person on the site lol

 

[michael_s_k]

Sorry, i didn't mean nor intended to sound that way, i was just stating that if it had been something you'd heard of, it could've been a baseless rumour.

Everything else i've listed is what makes up the upgrade that is a racing modification. As in, i've access to the actual files the game loads from what me and others have found over the years of reverse engineering GT2.
And with the way the upgrades work in GT2, the RM upgrade itself has nothing that suggests it affects aything else than the weight of the car and the downforce values, physics-wise.
This here is the data that makes up the RM of the 1996 Supra RZ, in its entirety.
View attachment 1204136

GT1 and GT2's racing modifications are not to be confused with GT5's version of it. In GT5, it's an entirely different car, with its own specs, parts, and settings, swapped in place of your previous car.
In GT1 and GT2, it's purely a cosmetic change, a toogle on the downforce settings becoming modifiable, and a "stage 4" weight reduction upgrade (although it isn't, hence the quotes)

I've just tried your expriement on my end and I can't reproduce the change. I bought 2 '96 Supra RZ, RMed one of them and checked their gears, they're identical (3827, 2360, 1685, 1312, 1000, 0793, f3266), as they should be, because i haven't bought the Full race transmission part.
After buying an other set of 96RZs, i first bought the racigg transmission, then I RMed one of them, and both have the same gear ratios of 3202, 2214, 1643, 1276, 1037, 0882, 3266 at the default auto level 10, which again, makes sense as those ratios are calculated taking the car's maximum engine RPMs and the auto setting's target speed value. Both of which the RM part doesn't affect.
For the sake of trying to match what you've told me above, i've set the gear ratios of both cars to auto level 17 and both have the same ratios of: 2884, 1912, 1383, 1050, 0837, 0700, f3266

However, i can tell you what parts can/will (and could for some) affect your car's gear ratios when you equip the racing transmission after buying/equipping said parts, because they have the ability to affect a car's maximum revs:
ROM, Engine Balance, Port/Polish, Displacement Increase all have the ability to add/remove RPMs to the engine. In fact, data-wise, they all are identical in what they can do. However, only Engine Balance was ever set to affect a car's RPMs (EB adds 100RPMs to all cars) by the developers.
Here's their data for the Supra 96RZ (note: I used the Skyline R34 V-spec's Displacement Increase upgrade as the Supra does't have any)
View attachment 1204118
Turbo Kits can also affect RPMs, but it's an other part genre whhere that feature was never used. (Supra 96RZ stage 4 Turbo here)
View attachment 1204119
Naturally Aspirated Kits are the only major power upgrade to visibly alter a car's RPM values, as they add upwards of 1000rpm to most NA cars in the game, at least those that can equip a stage 3. Stage 1 and 2 add just a few hundred RPMs to an engine's redline and maximum revs.
Shown here is the Stage 3 NA Tune from the 1996 Supra SZ-R, +500RPMs in this case.
View attachment 1204120
These all technically speaking have the "power" to affect a car's gear ratios, provided the gear upgrades are installed after the power upgrade. After is important, because the game recalculates auto gear ratios only when a transmission upgrade is applied to a car or you change the auto level/individual ratios.
If you buy a transmission upgrade before installing a power upgrade that alters RPMs, you'll notice that the gear ratios don't change.

As for the titanium exhaust tips, it's part of the visual upgrade because it's part of the 3D model of the RMed vehicle. It can also be part of the road model as well, it just depends of the texture applied to exhaust 3D mesh. And has zero consequence on the car's performance, such as drag coefficient etc. That'll be just a number in the body data.
View attachment 1204114View attachment 1204115

I'm not trying to discredit you or anybody else, however, i'm providing facts backed by my own, and other people's research on how the internals of GT2 work.
Hence why i've mentioned that it's either some form of corruption, false rumour or misunderstandings.

However, you've now made me curious as to why this would happen to your game, as it's defintiely not (i believe i've given enough proof in this post here) intended game mechanics, and i'd love to have either a detailed description of what you do, what the steps you take are, from buying the car, to when you notice the gear ratios changing, if at all possible backed with a video recording or screenshots, because i'm genuinely curious as to why it would happen.

Sorry about the long post, you've unfortunately for better or worse attracted the attention of one of the most knowledgeable (to the point of being borderline obsessed i'll admit) GT2 person on the site lol

Thank you for your kind reply. I am pleased to have been fortunate enough to have attracted the attention and interest of a GT enthusiast as knowledgeable as you. I appreciate the info you've provided, and it makes this puzzle more mysterious because I had already guessed as much and later verified based on the extrapolated game files showing exact changes for each modification in other forums. The data you've provided is exact as it is based on the specific model(s) in question in my case, but the basic idea is the same: the change in transmission settings aren't part of the intended game mechanics. So I too am puzzled by the change in gear ratios after performing the racing modification. As far as what modifications I make and adjustments to tuning, I, prior to performing the racing modification, add pretty much every possible upgrade in parts including but not limited to turbo kits or NA tune-ups, air cleaner and muffler upgrades, and all the rest including brake balancing, traction control and so on and may or may not make adjustments to the suspension on an ad hoc basis. As far as I can tell, nothing I have done is out of the ordinary and should not cause the gear ratios to change after applying the racing modification (nothing should, right?) and yet every time (so far) for every make/model/year of vehicle I have tested, a given vehicle's auto-set gear ratios increase slightly starting on I believe level five and continuing to the highest level. For some reason the first three or four auto-set ratios remain the same. But all the others are, as I stated, slightly higher as though the RM wants the vehicle to favor torque and acceleration over top speed. It isn't a huge problem as the bottom line is a decrease in top speed(s) of only a few mph, but it's still a huge mystery to me especially now that you've taken the time to demonstrate/verify exact changes as illustrated in the actual game files. So the question remains: Why do all my cars show an increase in the auto-set gear ratio settings after performing the racing modification? I'd be happy to provide more detailed information and even upload images of comparisons of the auto-set ratios pre and post racing modification and any other visual data you'd find useful (like a screenies showing all equipped and active modifications and tuning changes prior to RM). I have now spent four nights puzzling over this for many hours and I would love to arrive at a definitive conclusion as per the why and how of this apparent anomaly, and your expert-level knowledge as well as uber-enthusiasm would be greatly appreciated. Thanks again for your help thus far. I am happy at least to feel confident that this appears to be highly irregular if not completely unheard of and even impossible but as I mentioned sometime earlier, I had read scattered reports of racing modification making unusual changes to, for example, torque output, and in post GT 2 games, changes to the interior. But these reports might be false or otherwise based on a misunderstanding or prior oversight. Who knows? What I do know is that now more than ever I am super-curious as to how these impossible gear ratio changes are a reality for me. Again, I have images showing the before and after auto-set gear ratios and images comparing two different cars of the same make/model/year, one RM and one not. I hate to waste more time on this but, again, I am, like you, intrigued to learn how this is possible and why it is occurring when all indicators show that it should not and even cannot happen. So please follow-up with me with additional info, ideas, or requests for information from me. Thanks again!

 

[michael_s_k]

Submaniac - After reviewing the text of and reflecting further on the ideas presented in your last post, I realize that you had suggested or even stated (w/an example or two) that certain modifications (add-on parts or procedures like engine balancing et al CAN effect the auto-set gear ratios on post-RM vehicles. IE, certain modifications have an effect on the car in question's gearing after one performs the racing modification. Am I understanding this concept correctly? If so, I would love it if you could go a little more in-depth on this idea and let me know what information if any I may send you regarding the pre-RM modding of vehicles which after applying racing modification had slightly increased gear ratio numbers.

Since I usually perform the same modifications on every vehicle, with some exceptions on an ad hoc basis, this might explain why so far each RM car I have compared to its pre-RM state all have the same slightly increased gear ratio numbers. I am trying to think of which cars might be an exception and the easiest experiment to determine whether or not modifications are the cause of my mysterious gear ratio shenanigans. Perhaps race modification applied to a fully stock car, comparing the before and after auto-set gear ratios?

Please let me know what you think when you have a moment. And thanks again for your kind assistance. - Michael

 

[michael_s_k]

Submaniac - Ok, I tested my hypothesis. Purchased two used Suzuki Alto Works, equipped each only with the fully modifiable transmission, then applied the racing modification to Alto #1 and sure enough the R Alto #1's gear ratios were identical with the non RM Alto # 2. So your statement re: some modifications effecting the gear ratios after performing RM holds true and seems to solve the essence of the mystery of the strangely altered post-RM gear ratios. Now I wonder only: which modifications effected the gear ratios? It's not of any critical importance, just curious and can figure it out on my own by experimenting or you can hopefully provide me with a cheat sheet if at all possible. In any event, thanks for all your guidance. Mystery solved...right? - Michael

 

[michael_s_k]

Sorry, i didn't mean nor intended to sound that way, i was just stating that if it had been something you'd heard of, it could've been a baseless rumour.

Everything else i've listed is what makes up the upgrade that is a racing modification. As in, i've access to the actual files the game loads from what me and others have found over the years of reverse engineering GT2.
And with the way the upgrades work in GT2, the RM upgrade itself has nothing that suggests it affects aything else than the weight of the car and the downforce values, physics-wise.
This here is the data that makes up the RM of the 1996 Supra RZ, in its entirety.
View attachment 1204136

GT1 and GT2's racing modifications are not to be confused with GT5's version of it. In GT5, it's an entirely different car, with its own specs, parts, and settings, swapped in place of your previous car.
In GT1 and GT2, it's purely a cosmetic change, a toogle on the downforce settings becoming modifiable, and a "stage 4" weight reduction upgrade (although it isn't, hence the quotes)

I've just tried your expriement on my end and I can't reproduce the change. I bought 2 '96 Supra RZ, RMed one of them and checked their gears, they're identical (3827, 2360, 1685, 1312, 1000, 0793, f3266), as they should be, because i haven't bought the Full race transmission part.
After buying an other set of 96RZs, i first bought the racigg transmission, then I RMed one of them, and both have the same gear ratios of 3202, 2214, 1643, 1276, 1037, 0882, 3266 at the default auto level 10, which again, makes sense as those ratios are calculated taking the car's maximum engine RPMs and the auto setting's target speed value. Both of which the RM part doesn't affect.
For the sake of trying to match what you've told me above, i've set the gear ratios of both cars to auto level 17 and both have the same ratios of: 2884, 1912, 1383, 1050, 0837, 0700, f3266

However, i can tell you what parts can/will (and could for some) affect your car's gear ratios when you equip the racing transmission after buying/equipping said parts, because they have the ability to affect a car's maximum revs:
ROM, Engine Balance, Port/Polish, Displacement Increase all have the ability to add/remove RPMs to the engine. In fact, data-wise, they all are identical in what they can do. However, only Engine Balance was ever set to affect a car's RPMs (EB adds 100RPMs to all cars) by the developers.
Here's their data for the Supra 96RZ (note: I used the Skyline R34 V-spec's Displacement Increase upgrade as the Supra does't have any)
View attachment 1204118
Turbo Kits can also affect RPMs, but it's an other part genre whhere that feature was never used. (Supra 96RZ stage 4 Turbo here)
View attachment 1204119
Naturally Aspirated Kits are the only major power upgrade to visibly alter a car's RPM values, as they add upwards of 1000rpm to most NA cars in the game, at least those that can equip a stage 3. Stage 1 and 2 add just a few hundred RPMs to an engine's redline and maximum revs.
Shown here is the Stage 3 NA Tune from the 1996 Supra SZ-R, +500RPMs in this case.
View attachment 1204120
These all technically speaking have the "power" to affect a car's gear ratios, provided the gear upgrades are installed after the power upgrade. After is important, because the game recalculates auto gear ratios only when a transmission upgrade is applied to a car or you change the auto level/individual ratios.
If you buy a transmission upgrade before installing a power upgrade that alters RPMs, you'll notice that the gear ratios don't change.

As for the titanium exhaust tips, it's part of the visual upgrade because it's part of the 3D model of the RMed vehicle. It can also be part of the road model as well, it just depends of the texture applied to exhaust 3D mesh. And has zero consequence on the car's performance, such as drag coefficient etc. That'll be just a number in the body data.
View attachment 1204114View attachment 1204115

I'm not trying to discredit you or anybody else, however, i'm providing facts backed by my own, and other people's research on how the internals of GT2 work.
Hence why i've mentioned that it's either some form of corruption, false rumour or misunderstandings.

However, you've now made me curious as to why this would happen to your game, as it's defintiely not (i believe i've given enough proof in this post here) intended game mechanics, and i'd love to have either a detailed description of what you do, what the steps you take are, from buying the car, to when you notice the gear ratios changing, if at all possible backed with a video recording or screenshots, because i'm genuinely curious as to why it would happen.

Sorry about the long post, you've unfortunately for better or worse attracted the attention of one of the most knowledgeable (to the point of being borderline obsessed i'll admit) GT2 person on the site lol

Wow, I wrote a long reply to this message from you and somehow it did not post, much to my chagrin. I believe that the essence of my reply was to express my gratitude for your interest, acknowledge my good fortune at my post attracting the attention and interest of an uber-enthusia

Sorry, i didn't mean nor intended to sound that way, i was just stating that if it had been something you'd heard of, it could've been a baseless rumour.

Everything else i've listed is what makes up the upgrade that is a racing modification. As in, i've access to the actual files the game loads from what me and others have found over the years of reverse engineering GT2.
And with the way the upgrades work in GT2, the RM upgrade itself has nothing that suggests it affects aything else than the weight of the car and the downforce values, physics-wise.
This here is the data that makes up the RM of the 1996 Supra RZ, in its entirety.
View attachment 1204136

GT1 and GT2's racing modifications are not to be confused with GT5's version of it. In GT5, it's an entirely different car, with its own specs, parts, and settings, swapped in place of your previous car.
In GT1 and GT2, it's purely a cosmetic change, a toogle on the downforce settings becoming modifiable, and a "stage 4" weight reduction upgrade (although it isn't, hence the quotes)

I've just tried your expriement on my end and I can't reproduce the change. I bought 2 '96 Supra RZ, RMed one of them and checked their gears, they're identical (3827, 2360, 1685, 1312, 1000, 0793, f3266), as they should be, because i haven't bought the Full race transmission part.
After buying an other set of 96RZs, i first bought the racigg transmission, then I RMed one of them, and both have the same gear ratios of 3202, 2214, 1643, 1276, 1037, 0882, 3266 at the default auto level 10, which again, makes sense as those ratios are calculated taking the car's maximum engine RPMs and the auto setting's target speed value. Both of which the RM part doesn't affect.
For the sake of trying to match what you've told me above, i've set the gear ratios of both cars to auto level 17 and both have the same ratios of: 2884, 1912, 1383, 1050, 0837, 0700, f3266

However, i can tell you what parts can/will (and could for some) affect your car's gear ratios when you equip the racing transmission after buying/equipping said parts, because they have the ability to affect a car's maximum revs:
ROM, Engine Balance, Port/Polish, Displacement Increase all have the ability to add/remove RPMs to the engine. In fact, data-wise, they all are identical in what they can do. However, only Engine Balance was ever set to affect a car's RPMs (EB adds 100RPMs to all cars) by the developers.
Here's their data for the Supra 96RZ (note: I used the Skyline R34 V-spec's Displacement Increase upgrade as the Supra does't have any)
View attachment 1204118
Turbo Kits can also affect RPMs, but it's an other part genre whhere that feature was never used. (Supra 96RZ stage 4 Turbo here)
View attachment 1204119
Naturally Aspirated Kits are the only major power upgrade to visibly alter a car's RPM values, as they add upwards of 1000rpm to most NA cars in the game, at least those that can equip a stage 3. Stage 1 and 2 add just a few hundred RPMs to an engine's redline and maximum revs.
Shown here is the Stage 3 NA Tune from the 1996 Supra SZ-R, +500RPMs in this case.
View attachment 1204120
These all technically speaking have the "power" to affect a car's gear ratios, provided the gear upgrades are installed after the power upgrade. After is important, because the game recalculates auto gear ratios only when a transmission upgrade is applied to a car or you change the auto level/individual ratios.
If you buy a transmission upgrade before installing a power upgrade that alters RPMs, you'll notice that the gear ratios don't change.

As for the titanium exhaust tips, it's part of the visual upgrade because it's part of the 3D model of the RMed vehicle. It can also be part of the road model as well, it just depends of the texture applied to exhaust 3D mesh. And has zero consequence on the car's performance, such as drag coefficient etc. That'll be just a number in the body data.
View attachment 1204114View attachment 1204115

I'm not trying to discredit you or anybody else, however, i'm providing facts backed by my own, and other people's research on how the internals of GT2 work.
Hence why i've mentioned that it's either some form of corruption, false rumour or misunderstandings.

However, you've now made me curious as to why this would happen to your game, as it's defintiely not (i believe i've given enough proof in this post here) intended game mechanics, and i'd love to have either a detailed description of what you do, what the steps you take are, from buying the car, to when you notice the gear ratios changing, if at all possible backed with a video recording or screenshots, because i'm genuinely curious as to why it would happen.

Sorry about the long post, you've unfortunately for better or worse attracted the attention of one of the most knowledgeable (to the point of being borderline obsessed i'll admit) GT2 person on the site lol

I hope you were able to find my other messages which I posted without using the reply button. I am writing now to offer my heartfelt gratitude for all of your time, attention and information provided which ultimately resulted in my verifying your suggestion that certain modifications prior to performing an RM can cause increases in gear ratio settings once racing modification has been applied. As I mentioned in my prior post, I purchased two inexpensive '90 Suzuki Alto Works (same model), equipped both with only the fully modifiable transmission mod, then applied the racing modification to Alto #1 and compared its auto-set gear ratios to non RM Alto #2 and found their gear settings were identical. In short, mystery solved and thanks again for your thoughtful, kind and well-informed assistance which I deeply appreciate so, again: thank you! I am curious as to which modifications have what effect(s) on the transmission settings. If you have some type of cheat sheet with which you're willing to provide me with information regarding the effect of modifications on engine/transmission settings after RM. If not I am quite capable of experimenting on my own to determine specific modification RM effects. In any case, your input here has been incredibly useful and I offer you my humble thanks for your interest in my mystery of the RM altering gear ratios. Thanks again, Submaniac93! And if you have any additional thought, questions or general comments I would welcome any additional input. Again, please accept my humble gratitude, Submaniac93.