I have a oo, f-150 5.4L 4x4, I have a k&n airintake system. I up graded my exsust system, biger pipes, I exsust runs into one mufuler and duel out. I want to got to high flow converters, so should I take off the preconverts when I put on my high flow ones, or should I leave them on. If I take them off will it affect my system and pop a code; or shold I leave them on? Which way would be better to go to give me more hp and better gass milage? Will I lose anything by doing this mod, and will it give me alot of dron in the cab?

Thank you for any help you could give me.
jfox