I have a brand new Magnaflow stainless dual exhaust it is five inch from the turbo back to the muffler the inlet side of the muffler is five inch and the exit side has a y with two four inch outlets and the exhaust is four inch the rest of the way out the rear of the truck I bought it off of cummins forum thinking it was a five inch front to back so I recieved the exhaust opened it and saw it wasnt :nail: Im just wanting my money back out of it 600$ plus shipping I can send pix of exhaust through txt it fits 04.5-07 cummins, exhaust is brand new with no dings or dents never installed