-3.6 in the front
At that point i'm wondering if you are losing contact patch.
Has any one checked tire temps following a session? I am currently running
-2.5 in the front and -2 in the rear. Tire temps across the tread in the rear are pretty even. The front depends somewhat on the specific track (sweepers vs. a lot of tight turns) but overall it seems to be a good compromise.
Also IMHO some of this could also be due to suspension settings (spring stiffness, compression, sway bar, and toe)