Hi i just bought a 2004 F150 ext cab, with 5.4L. And i have some questions with the exhaust....I have a 40 series flow master muffler on it now. I was thinking about buying a set of purple hornie's and making the exhaust true duels with 3Inch pipe from cat back. What do you guys think? And will new high flow cats void the warrenty and are they worth the money?

 

Hi ktena Congrats on the new ride and welcome to the best ford site and people on the net.
I don't think you should go with true duels unless your pushing over 360 RWHP your truck will not have any bottom end punch
2004 Screw

 

cool sweet, i think im gonna go with flo masters american thunder system