sorry...in that last post i meant 3 1/2". i hope your piping is mandrel. my friend's got a 4 banger with flows and crimp bent pipe. sounds horrible and gives me a headache sometimes. course his is a yota.
I think that mandrel is where there are bends in the pipe it doesn't look like it's got ridges on the inside of the bend. And crimped bends have ridges on the inside of the bend...
Mendel bent is bending a pipe with the bends have no loss in diameter of the tubing. they usally have these like metal ball on a rope type thing that goes inside so it doesnt let the pipe deform when bending. His truck is fine with out mandel bending 99% of the cars on the road dont need it.