What size are your NT01s? Are they staggered or square -- as square should help reduce the understeer a bit. I'm planning to go to RA1s in a square config of 275/35 to help as well.
My track alignment got to -1.3 F and -2.0 R, but could go no further. This seemed to reduce the slow corner understeer issue considerably.
Dinan has front camber plates that add up to -.7. This may be an attractive addition.
Q: How did your lap time compare to the Cayman? I'm guessing the M3 was a bit faster around the track. True?