Front tire temps.
@ 2525# and 134 tq my car is hell on fronts. The GTI curb is 3150# (assuming it will probably be about the same with cage and driver after wight reduction) and 207 tq that thing is going to handle like shit toward the end of a race compared with a RWD car.
Also the GTI uses a shit McPherson design.
If the GTI ran at stock boost an ITR would rape it, the ITR probably could give it a few pounds and still win.