hey guys ive got a 2000 5.4 in my f-150 and i think one of my cats is getting cloged, i have a 3" y pipe back exhaust with a 40 series flowmaster. it sounds good untill above 3 grand then i get the classic vacume cleaner exhaust sound. i want to remove all of my cats and replace them with 1 high flow cat right after the y pipe, like the older f-150's had. i was woundering if anyone has done this or has any comments on me doing this, also since im going this far are headers worth the trouble and who makes them for our trucks. thanks!

 

I'm pretty sure you need to maintain the same cat setup as the factory to be truly legal.

Are you getting any codes?

Also, you've got 4 cats so make sure that you know which one(s) is/are plugged.

Long tube headers give some gains. Short-tube headers, not so much.

 

Hey Thanks! no i havent pulled any codes, relating to emissions/ exhaust/ cats, but that is also a concern if i choose to do away w/ the cats and replace them w/ just one cat, then im woundering if the sensors are going to go crazzy and make the computer messed up, a few of my buddys have done away with their cats on their trucks (93 ford ranger, pre obd2, and a 97 dodge should be obd2) and havent had any problems with the computer/ sensors. i apreciate the info, thanks!

 

i believe the two rear so cxalled cats are resonaters. the 02 sensors are in between the front and rear ones. all you should need to put on are the two fronts and keep all the 02 sensors. the rear ones do not need to be on there. only if the 02 sensors were mounted behind them would they need to be kept.

 

Fronts are called "pre-cats" while the rears are the "cats".

 

Fronts are called "pre-cats" while the rears are the "cats".