This mod was done on a brand new OEM muffler (E92), it was a take off from a M3 getting a performance exhaust. The mod was completed by adding solid piping for the long perforated pipes and capping the small perforated pipes. I also had the stuffing put back in the absorption chamber.
I love the sound on the modded exhaust, but I got a good deal on a full akra evolution exhaust so it has gotta go.
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