straight pipe. I've had a hole in my rear muffler for about a year now. My intention has been to just tack a straight pipe on the rear to move the exhaust gases out from under the car (still have to clean sooty black spot above muffler though). With the CC and the turbo already in line I don't notice much in the way of added noise from the hole; if anything a tiny bit of extra low rumble - I think it sounds cool.

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-livin' in the terminally flippant zone