your exhaust sound is made up in almost equal parts by your header geometry and exhaust system as well as the type crank your engine uses and its firing order. to assume you get a similar sound out of a fundamentally different engine just by transplanting a muffler from one you like the sound of is very optimistic, to say the least. by all means, do the job and report back with your results but i'm guessing that the guys in the know on here are right, your beemer will sound nothing like a mustang.

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