I have sec cats replaced with vibrant resonators, cat less DP, and magnaflow mufflers. I thought it would be louder. It's not much louder than stock but the tone is a lot deeper. The tone is perfect I just wish it was louder. I may go with Remus or the 335is mufflers.
2011 335is DCT, JB4 MHD BEF, stage 2 LPFP, e50 50/50 meth, FBO, MT ET Streets when needed