On the stock exhaust, just past the cat (going towards the rear) the exhaust pipe is squished to I would say about half of its original diameter to clear other components. Ithas me wondering other than looks and sound what good does the cat back do since this is in front of the bolt on system? Anyone that has seen this will know what I mean. At this point I am not sure that a cat back would give you better exhaust flow since the constriction is before the cat back system. Just something to ponder.

 

Yup, we all have the same deformed pipe...I don't think though itoffers any adverse restriction to exhaust flow...I got a Gibson duals Cat-back, with only the center muffler, and it sounds great.