I built a 2 1/2" "X-Pipe" system that runs all the way to the end of the frame horns on my roadster. It's ceramic coated, and mild steel.

What I found interesting was how long it grows in lenght from cold start-up to hot operating temperature. The tubular exhaust hangers are made to allow free "front to back" movement. The system grows almost 1/2" as it gets up to temperature.

If I were to do it over I would build with Stainless tubing next time. By the time you get the mild steel system ceramic coated, the cost "is a push", with stainless steel.