mandrell bent or no?

what is mandrell bent?

i just bought a muffler from my friend, should i go for the mandrell bent or ...regular pipe.....and how much does each cost?

I would go with Mandrel piping. You get better exhaust flow. It is a little more costly than regular, but it is worth it.

good luck finding someplace that does true mandrel bending too. most people do press bending and claim its mandrel when its not. mandrel will have the same diameter the entire length of the pipe even in the bends.