i have a 2004 f150 5.4 and i was wondering what exhaust is better i don't woun't to by a kit so what should i do to the entire exhaust system for performance and sound and should i run single or duel.

 

Cat Back exhaust kit are popular. I went the less expensive route and just replaced my OEM muffler with a Magnaflow. It cost just under $100. parts and labor. Do a “search” on the subject because there are hundreds of post about the subject

 

Pick single or dual for looks. Pick a system if you want top performance, or just a muffler swap if you care mainly about sound.