Why is T304 stainless steel better than other types of steel (mild, aluminized, T430 steel)?

T304 stainless steel has the highest corrosion resistance compared to T430 and other grades of stainless steel. It will never rust and is the strongest steel for use in exhaust systems. Painted mild steel and aluminized steel will eventually rust/corrode and fail over time when the coating of paint/aluminum easily corrodes through Why is mandrel bent tubing better? Mandrel bent tubing has a uniform diameter throughout the bend, a 2.5" mandrel bend would be 2.5" all the way through. This keep performance up and exhaust flow high and efficient, maximizing the performance potential of the system. A crush bent pipe is literally crushed into a bend, making the diameter smaller where the bend is made. A typical 2.5" crush-bent pipe could only be 2" in diameter (or even less!) at the bend. A picture of a crush bent (left) and mandrel bent (right) pipe is shown below. Why can't I just have any exhaust shop make an exhaust system for me? A mandrel bending machine easily costs in the tens of ...