All legality aside, will the 4.0 motor run any better, or at least as good as it does with a cat, if you just totally eliminate it? I ask because the cat in my 93 Cherokee has seen better days and is starting to sound like its full of marbles. If i just run it from the pipe into a flowmaster, would it still run fine? I guess what i should ask would be...should i shell out 100+ for a cat on an off-road only vehicle if its not going to do anything for performance?

Passing emmisions is not an issue in my state...if that makes any difference to anyone.

dude you can get cats for like $30 at Vatozone.

But yes, it will run fine.

Although emissions isn't tested in your state, it is still a Federal requirement that you cannot remove a cat, even on a non registered vehicle. You also have a VERY high risk of not passing the "visual inspection." Whenever you get inspected.

just get rid of it, if you really still wanna appear legal just hollow it out. Replaced mine with a glass pack, it was quite a bit more torquey. :smokin:

the only cat i got is the little bastard that keeps pissing on my seats.

Had the same problem with my 93, I just run a glasspack and have no problems

mine ran like shit without a cat, plus it smelled like ass whenever it was on. its not gonna hurt to just have a POS autozone cat on there.

i put just a straight pipe on first, and ran like shit and loud, so put a glass pack in its place all better runs great.

it runs better more flow.

I did it all...Cat, Flowmaster; no cat, flowmaster (best sounding); straight pipe. Taking it off won't hurt anything...its just one less restriction in your exhaust. I run straight on my comp rig, and just flowmaster on my CJ 8. so take off that gay cat :flipoff2:

I just pulled a 4.0 from my 2A and dropped it into a YJ with a cat - big difference on the bottom end, IMHO. I ran without a cat for a few years (no exhaust space - flat fender) and it had more top end power but the bottom end torque suffered. For lugging the motor at idle and most offroad situations, I'd use a cat. No cat and a free flow muffler was only a noticeable advantage on high rpm climbs.

Replace the cat. They can be had cheap for around $50. The exhaust fumes will be much worse without it.. if you don't replace it, you're just going to piss people off behind you on the trail because they will have the *pleasure* of breathing in all the fumes.

Appreciate all the info guys! Looks like ill try it without...if the fumes prove to be a problem(which im doubting as i usually drive alone or in the back of a pack) i can always throw one on. Ill let ya know how it does.

As Texas Blake eluded to...Its federally illegal. Plus it keeps all of our air cleaner. Run a cheap one, and if you can tell its there add power elsewhere.
I'm not into huggin trees, but if I can help out the environment, I will.
My $.02

Here's the help you've been given:

A) You'll get more torque with the cat.
B) It's illegal to not have one.
C) Why not help keep ALL our air clean.
D) It's cheap.

Guess you'll try it without it. :rolleyes:

Just cut a hole in the top, empty it and weld it back up.

Christ, the days when cats were USEFUL where back in the 70's when engines ran like ass, and even then they sucked.

you don't get more torque with a cat, at least I didn't, pete :shaking:
oh and a glass pack is cheaper! I will admidt though my exhuast smelt like good ol pollution afterwards! :flipoff2:

so if i plug my exhaust completely how much more torque do i get?

My only point was that it's not terribly expensive to keep the air clean. I realize it's cheaper to not use one at all.

I've watched guys on a dyno remove their exhausts in search of more HP and torque, thinking less backpressure is better, only to get less Hp and torque. So it made sense to me what was mentioned by Rock Tech. :flipoff2:

One way or the other, who gives a shit. What's wrong with clean air?

Get one just to keep the smell down. :flipoff2:

Pete

Point taken, but it still flows better w/o one. Better flow = more power. I'll keep my straight pipe roar :flipoff2:

a monolithic cat does NOT hurt performance on the average sized motor if the cat is properly sized. the meatheads saying take the cat off because it kills horsepower must be thinking of the ol pellet type cats from the eighties that suck ass. I hollowed the cat in my XJ and the only thing I got out of it was a nasty raspy exhaust note. My friend just told me he put a bottle jack under the cat and put a small crush in it to keep the substrate inside from rattling. He said it fixed the marble noise. If the cat is plugged, removing it and replacing it with anything will increase power, duh...

ne14jpn: I think I saw your rig a few months ago at Neuroc, it is a gold colored Rubi, you know, the one that is completely stripped down with no original parts except for the rubicon stickers on the hood, asshat :flipoff2: