@chris99: Metal Scouring pads are a great thing to reduce exhaust noise in case your m3w is above the 98db level. Easy to fix with a single bolt (I drilled 2 holes on the top and downside of the exhaust pipe, some 15 cm prior the end). Very easy to remove when not required.
It is amazing how a single pad in each exhaust tube reduces the noise.
Hannes once: Green M3W; 2013 now: Red 4/4 Sport; 2011 and some practical cars for use in real life
