I'm itching to do an exhaust swap but I'm torn between going custom or pre made(ie: fswerks etc). I'm wondering if there are really any differences. Like fswerks has dyno proven numbers but would a custom of the same size make the same power? I know it will be a different sound depending on the muffler. A custom shop will be able to cut my stock exhust and make it so I can reattach if needed. But will just weld the new one so I won't be able to just unbolt it. Last is the cost. It will likely be cheaper to go custom because I live in Canada. After he exchange and shipping of a pre made it will be expensive. I'm just thinking a pre made has been tested and thought out, whereas a custom will be a one shot, no testing.