I have a few questions for everyone dealing with dual exhaust (5.4 3V). I want to run duals from the headers, what size pipe should I run? I want nice stainless tips, what size should those be? I am planing on runing them out the side right behind the back wheels. I want the truck to be loud but not horribly loud and something that will sound good. If anyone could help, I would appreciate it (website would be good also).

 

Gibson has a system for the '04 F150 Scabs and Screws like you described but Gibson is not especially loud. I believe their stainless tips (tips come in the kit) are 3.5".

screwdrive

 

The pipe size from the headers to the exits will be constrained somewhat by the cat. convert. inlet/outlet sizes (note: you are going to run the cats, aren't you?). Unless your system is pro-fessionally engineered by someone with a dyno, you may end up with a lot of noise and a loss of low-end power.