Excuse the big posts but I had some spare time yesterday so may as well share my findings in the spirit of close racing. I have nothing to prove and am not interested in winning, I will not be running the C7R if the classes don't get split.
Those GT3 setups wont work as a race setup too well, too much camber on the back. Maybe replace camber with some toe in, open up the diff slightly on coast but drop the rear ride height by 5mm to get some power stability back. I will have a play myself and post before the race. I also was running without ABS as since the update it is quicker not to. The new ABS is cool and more realistic feeling but increases stopping distances if you lean on it (as it should!).
The GT2 tyre model is clearly different and isn't getting excessive tyre wear from the camber. They also warm up quicker AND last longer, clearly a lot of work to be done in this area as they should be softer and wear even quicker than the GT3's. I might ask the question on the AC forum.
The GTR feels a bit broken to me, while it IS fast it bounces all over the shop and feels like something in the suspension geometry is wrong. I don't remember it being like this for the race at Spa. Even so it is still the fastest GT3 in my hands by a few tenths but good luck keeping it on the track for 30 laps, respect if you do
