Well the best bang for your buck would be a muffler delete. It actually sounds good if you put a set of vibrant resonators or any resonator for that matter. Now if you have catless downpipes, secondary cat delete and muffler delete, then its going to sound way to loud and raspy. But just cutting off the muffler with the stock downpipes and secondary cats is def the best bang for your buck. it also = less restriction for the turbos.
[size="2"]Crimson Red E92 335i M-sport 6-speed with MHD custom stage 2+ flash only , 40% E85/93 mix,+ HRE P40S wheels, KW Clubsport, M3 sways,+BMW performance CF Mirrors, BMW Performance CF deck lid spoiler,+ CF interior trim, p3 vent boost gauge,+ LUX angel eyes (11.73@124mph on street tires)