Basic GT1 to GT2 setup conversion guide:
We'll use the FZR as an example. A good setup for a GT1 FZR goes something likes this (for kyoto gp long):
Springs: 120/100 (rear/front)
Antirollbars: 115/40 (rear/front)
Dampers: REAR 9/12 (bump/rebound); FRONT (6.5/8.5)
Ride heights: 80/75 (rear/front)
Gears: 3.77/2.55/2.00/1.63/1.39/1.22 and final drive 3.22
Differential: Clutchpack LSD 50/70 (power/coast) with 650-750 preload
Tires: R3 all around, front pressures 145 kPa, rear pressures 220 kPa, camber adjust values -0.9 front and -1.4 rear (for the above spring stifnesses and ride heights this results in the live cambers of -2.28° on front and -2.22° on rears)
Downforce: 10/15 (front/rear)
Steering: max lock, max caster, 0 front toe and +0.3 rear
Now if you are about to make a GT2 setup out of that you do this: leave the suspension alone, leave the gears alone but increase the value of final drive to 3.400 (this makes the gears closer together - shorter). New peak power rpm is 7600 rpm instead of 8100 so the new shift point is 8000 rpm instead of 8500, do not wait for the shiftlight, just shift at 8000 (cant be bothered explaining why). Since the car has much less power and will not power-oversteer like a GT1 you will need more wing on front (or less wing on the rear) but you need a lower overall downforce - so look at the distribution. The GT1 set with 10/15 has 33.7 % downforce on the front, you need more than that but with lower wings - 8/12 wings gives you 34.2 % on front so use that (or 7/11 or 9/13 depending on how much df you want). DO NOT BE STUPID ENOUGH TO SAY "oh it has 350 hp and doesnt need almost any df so let's just put zero or something like 1/5". The air drag rises exponentially with top speed, you are doing 40 km/h less in the top-speed department with 150 hp less, you can almost leave the same wings as a GT1 car but since there's no power to provide you adequate cornering speed go with a bit lower wings (not a lot, a bit). Since there's no power, even with more downforce to the front, the car is bound to understeer on power - so increase the differential power locking to max (80 %). Tires.. use a softer compound if you can handle the temperatures and not ruin the tires, so max pressures R2 tires (240 kPa on the rear and then balance out the front with 160 kPa or something similar). Steering, since there's no power at all and even with more downforce on front and more locking in the diff you will still understeer, so just remove as much rear toe as u feel comfortable with (I have 0 rear toe on the GT2 set, you might slide around with that value, so try +0.1 or +0.2 but +0.3 is prolly too much).
That's about it. Change downforce, increase final drive value by 0.150-0.180, softer tires and generally more oversteer because you lack the power to produce it. GT2 setup is done.
Written by Scipy
...or simply ask people to share their sets