Alot of peole speak the truth here, a few talk crap.
As the wise guys know - firstly, it's subjecttive - fast as in what, acceleration, track (which track), stock, tuned, race car or road car?
Or just the fastest full stop?? Which is used for what??? Er....going fast...??
The RM'd EVO, TC and HKS are all pretty "fast" in terms of performance, but if you don't set them up right then you might aswell be driving an EVO 1 from '92 or whenever it is. You get a setup anything other than "good" then you're going backwards. Unless you're racing against other guys with crap setups too.
For road cars, online track racing, the ones to go for are definately:
EVO IV rs TM
EVO VIII MR
As mentioned, most "RS" EVO's seem to be better than the premium GSR's, but this is not uncommon, I've seen favouritism for standard versions of car over premiums with a few brands (like the R34 skyline too).
The VIII MR is just an beast, whether it's stock or tuned, throw it around Autumn Ring (stock, just engine and chassis rebuild) then do the same with other EVO's.... Straight away you can tell the difference.
I love the V and VI's EVO's, I've been racing different EVO's (road cars - sports tyres) online now for a year, compared to the Scoobies the EVO are crap, but, use a good one, find a good setup and choose your track and regulations carefully, then you can definately raise some eyebrows from some very puzzled Scooby drivers wondering what the hell you've done to that car..
Scoobys, just buy, jump in a go fast, EVO's take alot more work, but stick at it, choose wisely, tune wisely and you can be rewarded.
Also, as mentioned above, get rid of the AYC and go for a custom LSD, I do this with all the EVOs (that have AYC) and it takes alot less time to get them setup well.
Most of the guys I raced with who also like EVO's have made that change too...
But don't expect miracles, it won't happen. Bide your time and wait for the right moment..