I am doing a "do it yourself" turbo for my 95 M3. I am using a GT35 that will feel my fully built engine. I've been told to use 3.5" from the turbo back. Which muffler should I use? I've been checking out the Borla's, specifically the XR-1 Series. Can anyone give me any specifics they've used or heard of from their own experiences? Thanks a million.