Ok, I had a Magnaflow hi-flow cat put on a while back ago. After it was installed, the exhuast was louder than before(Trubendz catback with Magnaflow and optimized y). I thought it was an exhaust leak and meant to get it checked out but I honestly got used to the sound and it slipped my mind for a bit. There doesn't seem to be a performance loss which is why I probably didn't make a big deal out of it. ANYWAY, my question is does a hi-flow cat make an exhaust louder or should I get it checked out for leaks? And while I'm posting, I might as well ask if replacing the small 2.25" piece of stock exhaust that is left between the cat and catback with a piece of 2.5" will make any, if small, performance gains?
