The current exhaust setup on my 2004 Ford f150 Lariat (5.4) runs through the OEM exhaust pipe. I had the stock muffler replaced with a flowmaster 40 series and added tip. I was hoping for a little MORE added rumble without messing up the engines or too little back pressure.

From what I was able to find 2004 f150 have 4 cats and those first ones on each side is the actual cat the next one on each side is a resonator.

Will cutting 2 cats (which one, front or Back?) out and replacing them with high flow cats give me the desired increase in noise? Will it throw any codes?

What about all cutting all 4 cats and replacing them with 2 high flow cats. Is this too risky and will it also throw any codes?

What model high flow cat is recommended?

What do I need to make sure the muffler shop does as far as the o2 sensor (like installed 6” or less from back of last cat)

I don’t care about emission standards but want NO codes thrown.

Anything with warranty issues?

What are my options?


Thanks for the help

 

you should be fine with cutting all four out and replacing with two high flow cats just make sure you properly reinstall the o2 sensors ussualy about 6 inches away from the cats!!

 

my question is do you have a programmer for it? if so, when you throw a code, just clear it

 

All right. So I got under the truck this weekend and checked things out. Per side I have an o2 sensor then the first cat. After the first cat I have another o2 sensor and then the second cat. After the second cat there is no sensors that I can see. Am I missing another o2 sensor?

If I replaced the last cats the computer wont know the difference, correct? It wouldn't matter if I replaced them with pipe or high flow cats because the o2 sensors are not going to know the difference. Is it more complicated then that?

Is there any gain to be had by removing the last set of cats? Would it increase the noise and/or help in power at all?

I do not have a programmer nor is it in the budget any time soon. I do not want to deal with any codes or back pressure issues. Would I have any problems with replacing the last set of cats? Currently I have a flowmaster muffler single in dual out setup if that changes anything.

Thanks for the help guys.