1/4 mile runs are definately hard on these cars when you increase torque so much. Driveline flex and wheel hop need to be reduced if you want to continue your 1/4 mile charges: stiffer subframe bushings (m3 at least), differential bushings (at the same time to reduce duplicate labor), m3 rear links and MR rear toe arms. Then your car will be better equipped to handle that torque at the track.
2007 E90 335i, TiAg, 6AT, ZPP, ZSP, ZCW, 6FL, HD
Quaife lsd, ETS fmic, GIAC s/w, Dinan intake/exhaust/oc, Koni/M3 susp, Apex Arc 8, Mich PSS