really make a diffrence
I think you mean mandrel bent? Yes it makes a difference it makes for much smoother bends. Basically as the exhaust is bent there is something inside the pipe that helps it keep its shape. If a mandrel is not used the pipe will deform and not be smooth through the bends can be a decrease in diameter at the bend or a series of small kinks depending on the bender.
okay cause i had done my exhaust likt the cobra threw under my diff really messed with my bak pressure