I have a Supra RZ with 1073HP and very little oversteer. Here's my setup for it.
springs: 14.2f, 6.2r
height: 125 100
bound: 6 6
rebound: 7 7
camber: 2.8 1.7
toe angle: 0 1.0
stabilizers: 4 5
brakes: 18 16
limited slip;
initial 18, accell. 47, decelleration 30
take note of the height. Use TCM/ASM as needed as well as any kind of gear setting that matches your driving. The height is essential because the supra is very nose heavy. It'll prevent too much over-steer. It won't fix ALL over-steer, but it'll keep it to a minimum. Just have a light foot on the pedal and you'll do fine.