lol gt2 race car mods? Like stickers.... OOOO VROOM VROOM MY pepboy and my energizer bunny stickers make my car faster hahah.
All i wish in GT4 is if they had alot alot alot alot more upgrades. Theres a zillion

things you can do to cars not just turbos, port polish, n/a tuneups, etc. Also different sizes turbos, intakes, huge incoolers. So many different things possible to do to engines , different breaks, injectors, cams.....i can go on and on maybe even boost controller, also alot more upgrades for the suspension. I were alot more rims to chose from and i wish they did the rims in 3D cause they look like crap in game. Also another improvement would be the level design themselfs, if you ever change to 3rd person view and look how awkword the graphics between the car (lighting, quality, gamma) to that of the plain jane backround and level design. Its poo poo....
Body kits? Exausts, lalalala so many things to do to cars. I wish the came was alot more custom, once a month new parts added and you download them. SWEET! Also real company parts. I just wish there was alot more customization to the car. Street car tuning would be sweet, im not saying make it so you can put in a system and neons heh. You should get my point though, i hope GT4 is good though.