With Bmw reinforcement plates the subframe is fine. The balance is not lost at all, it actual more in the center in the car than ever. Remember this is a all aluminum block, the only difference you would notice is the cars acceleration and rumble out the exhaust. We have tested this swap in another 3 series for over a year before finalizing all the parts for the m3 we just built. If you’re ever in the area, stop in I will take you for a ride that may change your mind.