I have a single cab 2003 f150 short bed with the 5.4 L, i just got my friends stock exhaust system off his lighting and i was wondering what i should do about cats and mufflers. the setup is that the stock system hooks up to my headers then goes through cats to an x pipe then to two mufflers with side exit before the rear right wheel. i was wondering if i should keep the cats on or off, and if i leave them on will it really make it that much quieter? and should i use magnaflows or flowmasters?

 

Your truck has 4 cats and 4 oxygen sensors. The front O2 sensors you have to keep and therefore you need the frist two cats. If oyu want, there are quaility high flow cats availible. The rear cats and O2 sensors can be removed and you'll want MIL eliminators.

 

stock Lightning ext is not that loud, since there ARE two mufflers, the mufflers have been replaced, stocks L's only have one muffler, so it should bolt right up, but u may have to make some hangers for support, the stock L exhaust comes with 4 cats and 4 O2's also so they are all good, if u want to get rid of a set of cats, i would go with a set of high flow cats with a place for the 02's on the inlet and outlet, a L tuner, (JDM) has a full system for the L's which i recently put on, and that is the setup..


jim