I am not real knowldegeable on this subject. Does a performance exhaust enhance gas mileage? I was thinking of a cat back system or dual exhaust. If it does, which is preferred for a 1999, F150 with 5.4L? The application would be for daily driving not competition. I understand there might be conflicting opinions on this. If there is already a thread out there on this subject, let me know and I can check it out. Thanks

 

I put true duals on my 97, 4.6 and on my 07 5.4. Didn't do a whole lot for the 97 but the 07 liked it. MPG may go up a lil but the fun factor is a lot better. Since there are already dual cats just cut out the Y and dual it from there.