Originally Posted by ussoldierforhire
I think the difference is negligible. Macht Schnell claims gains of 9-14hp and AA claims 12+ hp. Both claim factory harmonics stay in tact. Only differential I see would be price and AA has a $50 off sale right now.
Major differentials are the AA is single pulley system and uses a proprietary belt. MS uses two pulleys (not affecting A/C operation, which would also spin slower during everyday driving) and normal off-the-shelf belts for when replacement time is neeed (normal maintenance).
Just things to keep in mind when shopping.
Originally Posted by tbone28
Forgive the noob question here (my 1st BMW)...I'm coming over from the mercedes world, where I read enough stories (to make me worry) of aftermarket AMG pullies falling off.
Is that a concern on M3's?
Not a concern since the BMW pulley is separate does not disturb the harmonic balancer.