How the hell do you get rid of the last cat on an 03 4.0 4wd? there are 4 cats, i want to at least get rid of the last one to get a little more sound. There are two mini cats comming off of each header, the two pipes combine into one cat (with o2 sensor so that one stays), then a SQUARE pipe connecting from that cat to the last cat. ITS SQUARE!! WTF!! I was going to cut it off right before the last cat and run 2 1/2" pipe to my dumped flowmaster, but how do I connect round pip to that square pipe? wtf?

 

its not square its flattened on the one side for clearance if i remember correctly.

 

keep the cats man.

The first 2 are pre-cats, the first cat is a reduction cat, this breaks down all the crap in your exhause and sends it to the oxidation cat(the 2nd one) and it put the **** that was broke down together with other stuff to make a cleaner exhaust and to lower pollution. Just keep the cat on there. They do not really affect you hp or anything like that.

This is in la-man's terms. i dont feel like typing out all the specifics, it will take to long and no one really cares.

Taking them off is so stupid. just keep them on there. If you want loud ditch the muffler or but a SBC and throw that in.

 

Didnt someone take the last two cats off and got better MPG?

 

I bet it was from their stock cats being clogged then.

 

If the cats are not clogged, then they have a very very minimal restricion on the exhaust flow.

 

Meow

 

I don't get this I need more sound crap. My buddy has 01 3.0 with a dumped chokemaster with all cats in place and it is really loud. My Magnaflow Catback is loud when I punch it. Are you guys deaf or do you want to be the loudest truck(aka a$$hole) on the road?

You want sound buy a V8.

 

Loud + V6 = Seriously

 

the first two are just resonators. they arent actually cats. the last two are cats. i wouldnt take them off. just run your pipe right after the last cat and call it a day

 

I had a 40 series flowmaster on my 4.0L ranger and it was plenty loud with all the cats. It droned a good amount on the freeway too. I definitely wouldn't want it louder than that.

 

Ditto

 

ya it sounds good, just a few of my buddies have diesels with stacks and straight pipes, and Im always with them, cant hear my truck over theirs, one of them told me to take the cats off, he has a 2500 dodge cummins with no cats or muffler, just straight pipe sounds sick, not that a gasoline engine could ever compare to it, nor could a 4.0 compare to a v8 sound, just kinda wanted a little more.

 

It is a ( FEDERAL CRIME ) to remove your cats!!!!

 

i removed mine only to gain clearance, but i then installed 50 state legal aftermarket high flow cats. i am not a fan of removing them but in my case it was needed to suspension changes.

 

If someone gained power from removing their clogged cats they are missing out on some more if they would have replaced them it should in theory return back to stock. I run a flowmaster 40 series delta which helps major with the v6 drone i tried running with out a muffler and the truck performed like poo. want more power and sound run headers high flow cats with a cat back.