Just because were on the subject I put my hands up to each of my muffler tips while my car was running, the two outer pipes (so if they were lined up 1-2-3-4, 1 and 4) seemed to have the most flow, so maybe the quad is somewhat useless, restrictive even, I don't know just a thought. I have the SPT for reference, I am considering getting a custom dual exhaust from a local muffler shop in hopes that it will sound like the nameless muffler delete system, but it'll probably sound like crap and be way too loud for highway use.