all depends on what kind of vehicle it is going on.....also what piping, muffler, tip, and other things they will be using on it......generally the best exhausts have stainless steel piping, a straight through muffler, and the bends are mandrel bent
its going on to an 87 buick century they guy also told me if he could fit 3 1/2 pipe he would use that or the next biggest that would fit and it is stainless steel.
the only reason for me getting this is tgat my current exhaust sounds like **** because i think my muffler is plugged and just wanted to change it and he offered me this