Where I live, it is a legal requirement to have a working cat on your vehicle. My personal opinion (not to sound too tree huggerish) is that it helps the environment, and may also help keep some of the eco-extremeists off of our backs (the four-wheeling community that is). I vote to keep it.

 

its a federal law to have a cat.

keep it.

exactly, the eco extremists will have a field day, and they will say we have an irresponsible community and it fuels their damn fire.

i vote keep it. there are no performance gains really. keep it and enjoy the FM40...hope that helps.

 

5.2

I dont really care about what hippies think when it comes to my vehicle (still has all smog equip so dont get panties in a bundle)

you have the 5.2 it will sound pretty burly to have straight pipe to FM40. Def gonna be loud though.

If its your DD, I wouldn't do it just on part of the noise.

On my 5.2 I have no tailpipe, just the little stub that comes on the FM, and its pretty loud.

 

yeah the other part of me thats worried i had a grand prix with no cat and just mufflers and the local PD would always ticket me for it and i dont feel like getting harrased like i did with that. yeah its deff my DD...

 

in michigan we dont have any inspections, will i notice a decrese in milage?i just dont want to get suckerd into somthing and then regret it later on

 

right now i only have a high flow cat... and dump the pipe right there... it sounds mean as hell when i get on it, but it kinda sounds like a boat when it is sitting there at idle... i actually want my quiter so i can go into the pits and stuff and not wake the world up when i drive... it is cool for a while then just gets old..

 

also a cat is a spark resistor...so if you are offroad and you get on it...there is a likely hood of causing a fire...i've seen it happen in race cars.

 

Bingo! It's definitely a safety issue. Though it's difficult to enforce, if you take a look at wheeling events like Big Dogs -- they require some sort of spark arrestor...

 

I agree, I don't care what hippies think either, but there is really no reason to not have a cat on there.

 

Keep that cat.
1) it doesn't restrict flow and performance, at least not enough for anyone here to notice. Its not one the beaded cats of the 70's, it has plenty of flow ability.
2) is the responsibile thing to do, it protrays a better image of the wheeler community.
3) You said you dont want it too loud, so you should keep that cat, even though it doesn't cut down on the sound much, if at all.

 

If you didn't sell the cat when scrap prices were high and platinum was through the roof, keep it now for reasons listed above.

I had been planning to cash mine in to finance replacing the muffler and tailpipe, but I procrastinated and prices have cooled down, so I guess I'm doing the responsible thing.

 

well after hearing greenzj's jeep im gonna do what he did and straight pipe it after the cat so thanks for all your guy's input!

 

What are the cats going for now-days? I just replaced mine with a magnaflow and need to get rid of the OEM one.

 

Well i ended up taking my jeep in so they could actually look at the cat. and turns out it, it was bad so for now i had them do a temp fix until i get my taxes back to buy a new cat but as a temp fix i had them cut it off and put a test pipe in place into a Flowmaster 40 series sounds good and was relativley cheap only $100

 

All this talk of cat or no cat.....what are you girls???? Get a dog

As for your exhaust run whatever is legal in your state/province. Better to be caught with one than without one....same rule goes for condoms.

 

yeah i figure once my tax return or my paycheck comes in ill go cat shoping lol and x2 on the whole dog thing i got a husky even tho hes kinda a pain in the rear

 

Have the Cat

My dad has a '87 Comanche that was restored. He had the exhaust replaced, but kept the old cat. Later on, a Comanche forum that he is a member of said that the compression gets messed up or something. Anyway, we replaced the cat and she runs almost just a loud and does not smell like bad eggs.

 

Thought id reply to your thread.Im running exhaust no cat straight to superflow muffler.I have 1993 5.2 jeepgrandcherokee.The problem with no cat is they tend to run rich.You especially notice idling in the cold.So if you dont mind the smell of fuel lingering in the air you will be alright.Depending if your trying to save money or what your budget is at the time.If you have the budget.I myself am working on replacing my exhaust with New polished headers 3"y pipe into 3" high flow cat 3"mandrel bent pipes all aluminum,superflow suv 70 series muffler with 3" stainless steel angle cut exhaust tip.

 

Old thread, but I had a 93 ZJ 5.2L that I ran with out a muffler. right off of the cat, there was a turn and it came out right before the passenger side rear tire. It sounded great. That is one thing I kind of miss with my 4.0L WJ.

 

Keep the Cat

Like stated above its the responsible thing to do. While noise is not really your issue, having gone down that route with a flowmaster, the rumble gets really old. Having to shout to be heard in the cabin gets even older and not being able to hear the stereo without cranking it gets older yet. When my Flowmaster was at the end of its life i swapped it out for a Magnaflow from Kolak and I can hear again,... and the Magnaflow is all stainless steel and was cheaper than the Flowmaster.

 

If restriction is a concern, you can get hi-flow cats that will flow well beyond the hp you're putting out. They're kind of expensive (as with all cats) but you'll be legal, and responsible. I know in this state it's illegal to not have a cat, and the state I used to live in was also illegal to sell a vehicle without a cat. So, keep the cat, if you feel it's too restrictive get a hi-flow cat.

Also, on my trans am when I put in the race pipe (cat removed), it messed up the rear o2 sensor, and had to be deleted out of the computer. That's also something to keep in mind.

 

Keep your cat I have a 5.2 and I dumped the cat when I had my FM40 installed. Can't keep the Check Engine light out, and it runs really rich. Also I'm sure the OX sensor is toast by now too. As far as the sound I think it sounds harsh and raw. I have heard other 5.2s with 40 series installed with cats, and I think they sound much better.

 

Good stewardship and pissing off econazis aside, your jep has an 02 sensor after the cat. When that sensors doesnt show a relative increase in 02 after the cat it assumes the cat has failed and causes the engine to throw a code and run lean.

 

Good stewardship and pissing off econazis aside, your jep has an 02 sensor after the cat. When that sensors doesnt show a relative increase in 02 after the cat it assumes the cat has failed and causes the engine to throw a code and run lean.

idk about that mine only had one and my dakota had a 5.2 and only had two right at the manifolds. what im goin to say next mihgt make some ppl angry but mine when i got my zj it didnt even have a cat form the previous owner and being a cert. auto tech i went to summit and bought a high flow cat form magnaflow to imporve gas mileage and not burn out my valves. i gotta heavy foot but when it comes in im matching it to a flowmaster 70 series they sound deeper than the 40. the 40 drones too much

 

with the way the 4.0 is you don't even need a cat my brother in law had an XJ with no cat it sounded awesome the only thing you could notice is it would kinda back fire when slowing down which made it sound like a hot rod really. so if you want no cat go with no cat the emissions won't change it will not read any high with or without the cat and gas mileage goes you won't see a change.

 

Well it also depends it you have the 4.0 or not the 4.0 i know you can go without the cat and have no prob the V8 i don't know about.

 

While you think you dont have a problem, your computer is doing things to your timing and fuel maps that is impacting performance. It may be imperceptable from the drivers seat but it's happening. You cant simply tell the computer to ignore the signal or loss of signal from the O2 sensors.

 

if they made a cobb system for jeeps then yea you could but since they dont i guess not