Hey Xnewmanx, I'm just about to give a try at welding a set of straight pipes to a 550. I'm wondering if you remember what diameter pipe you used? If you used a coupler or some sort of connector from the headers to the pipe? Any tip would help on the process, as it's my first time tiring to tackle an exhaust weld like this. An I just wanted to double check the stock headers of a 550 are stainless steel, yes?