BMW S55
BMW S55 Tuning Guide: M2 Competition, M3 & M4 Stage 1, Stage 2 & Best Upgrades
The BMW S55 is the twin-turbo straight-six engine found in the F80 M3, F82 M4, F83 M4 Convertible and F87 M2 Competition. It is already a serious performance engine from factory, but with the righ...