I don't know if you have this but check your EZ-pass. The sound was bouncing off the dashboard, almost went to the dealer for it.
Bilstein B8 Euro-spec struts, Bilstein B8 shocks, eibach pro-kit springs, Remus exhaust, stage 3 intake manifold,Stage 2 AA tune, BMW Short shift kit. Silicon intake pipe. M3 control arms front, M3 rear. ECS trailing arm with whiteline bushings. Purple powerflex subframe bushings. Yellow power flex upper shock mounts. Single mass flywheel OE weight.