I'm considering a 4 inch exhaust for my 02 lb7 Which route is the best to take, from the turbo back or from the down pipe back. I don't have to worry about a cat...since it didn't come with one. thanks

I would do a turbo back. The turbo back systems don't really go all the way back up to the turbo they connect to I am going to call it turbo outlet pipe. I have a 4" turbo back MBRP on mine and love it. It does hit the tranny cross member a little I am not sure if that is because of the way that I installed it has anyone else had that problem?

The turbo-back is actually a down-pipe back system. Same setup, manufacturers word it differently though. The main two are down-pipe back and front-pipe back. The front-pipe back kit will bolt up to the 4 bolt flange. Either system will get great results. The front pipe is 3.5" straight through so if you want to save a little over $100, just go with the front-pipe back kit. if you have any questions, give us a holler.