Our M3s have very little sound proofing, especially in the trunk. The plastic tray for the air compressor & fix-a-flat is all that separates the trunk from the exhaust. The Akra slip-on is quiet compared to most of the other exhaust available, If you want it loud you should try a Gintani Race.
09' AW M3, 6MT, Black Novillo Extended, Carbon leather trim, Premium, Moonroof, OEM Carbon spoiler, BMW LED Int. Bulbs, Avant Garde 19x11/19x9.5 M310 wheels, OOLux V3 AEOO, Vorsteiner Type II diffuser, Megan Racing Stainless exhaust, Benvo Stage 1 tune, Dinan High Flow Carbon Fiber Intake, Dinan Front anti-sway bar, H&R Sport springs, 30% tint