'99 - '05 GMC/Chevy 1/2 ton, 4.8L-5.3L, Off Road / Cat Delete, Tru- Dual Down Pipe Kit. Fully welded and flanged for DYI/Easy Install. Even has O2 Sensor bungs welded in place. After this is installed it's ready to have tru-daul exhaust built for it the rest of the way, which can easily be done by a good exhaust shop. We used an actual truck to build this, so there should be no fitment issues. Seals and gaskets are included. The pipe is "2.5 o.d., so I suggest a cat delete tune to keep your gas mileage, if you don't want to deal with a cat delete tune we have a smaller version so you don't lose all your back pressure. We're a Custom Performance Exhaust Shop so we can build the rest of the system or a custom system that you want, don't be afraid to ask, we'd be happy to help. We've built these systems for our own vehicles, so they've been tested and proven by the people that build them.