Just got the urge to put dual exhaust or bigger single, whatever it may be, on my 2002 ext 4x4 4.0 SOHC. The cat converter on my stock exhaust, if it gets cut out to accomidate the new exhaust will it throw codes to the computer and make the check engine light come on or will i be good? Dont want loud, just want better flow for more power and MPG. We dont have the pollution check crap here in mid MO so inspections and what not isnt a problem, would rather the cat conv wasnt there at all.
Thanks in advance and hope i put this in right area, couldnt find anyplace else.

 

A cat back will get you louder no noticeable gains in mileage. You may lose low end torque getting you to push the skinny pedal more.


If you want mileage, look into a tuner with a lower octane mileage tune.

 

SCT X3 seems common on here with good gains. I have the superchips and for a generic it does just fine.

 

But if i cut the factory exhaust off to put on duals will it play hell with the computer?

 

it should throw a check engine light if you remove the 02 sensors and it will not run properly. the computer will revert to a "base" engine map so the will run... but it may not be able to adapt to temp change and other factors. i have a dual exhaust on my truck WITH cats and noticed no difference in power or mileage... only sound

 

Removing the cat

one will set a CEL

two its illegal

three it is already a high flow cat so it gains you nothing but louder exhaust


If anything removing the cat will put the engine outside the computers acceptable configuration range and hurt mileage. There are work arounds for the CEL but you really don't gain anything like you think, maybe in the 80's you would. These engines need new heads and cams before anything else begins to not flow enough.

 

The last cat isn't monitored so if you absolutely had to take one off I would just remove that one...thats what I did when I got duals put on