wow, look at this guys? A question that actually has some
detail to it!!!

Instead of just: "can u toon my NXS???"
Sorry i can't go into detail here, it's been awhile since i played GT2, but i would try raising the car to about 120 mm, but leaving the rear
10 mm lower than the front. This keeps the rear portioned anchored while you're up on those banks, instead of getting loose (which is how spins can usually start).
Also,
soften the springs & stabilizers Everyone seems to think stiff springs and a lowered suspension are the best cure for all. My experience has been that with mid-engine cars in GT2, such settings make them too nervous. That's just me tho.
try setting your diff like this: 25/35/20. Put a good bit of camber up front (like 3 degrees) to keep your front tires from having too much grip reaction. You can also add some +toe as well, but not too much.
Also, use soft or supersoft tires if you have to. Sucahyo proved the Ai were using good tires in this race awhile back, so don't feel like you shouldn't. You can also try mixing tires so that you've got soft tires up front and supersoft in the rear.
...anyways, hopefully someone else here who's currently playing GT2 will come along and go more into detail than i have.