i have a buddy with an ext cab 4.8 and he just has a single in and dual out flowmaster, but he has the two pipes comming out on the passanger side so he didnt have to worry about the gas tank. it sounds really good, the only thing i've noticed with his,w as at wide open throttle at about 4500 RPM's it gets a little high pitch. but your normal everyday drive its perfect. its makes the truck look great too!