I'm not sure of the M3 dynamics but M4's when pushed hard tend to understeer. Power oversteer can be induced out of corners with too much throttle too early but steady state corning on the limit of traction, we've found they understeer more than oversteer.
On a ZCP M4 street/track setup, this provided the fastest lap times.
MP HAS with camber plates, 3 degrees camber, 2mm toe out CS coded shocks, smaller CS/non ZCP front sway bar.
2 degrees rear camber 2mm toe in. ZCP/CS rear sway bar (stock), GTS coded Diff.
Wheels and tyres, front 19x9.5 ET20 with star spec (GTS) 265/35 Cup2's. Rear 19x11.5 ET45 with Mustang GT350R spec 315/30 Cup2's
Roll Centre is a good adjustment to balance the car and for most tracks, the rear ride height is around half an inch 13mm lower than the front. Raising the front ride and lowering the rear for example induces understeer and vice versa. Here's my M4 in street trim, a bit higher and less front camber.
