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Discussion Starter · #1 ·
I was wondering if anyone on here knew if cutting out the cat would cause the check engine light to stay on. I had a dodge dakota and when i eliminated the cat the light stayed on and I don't think it ran as good. I am trying to figure out what I want to do with my exhaust but I still want my jeep to run effeciently. Thanks for any advice!!
 

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You gotta have the cat, for the exact reasons you just stated about the Dakota. It won't run right, and the light would stay on. Not to mention, you'd be breaking the law.
 

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besides it would probably kill your power. you would be far better off with a high flow cat. that will give you more power than no cat at all. not sayin that you'd feel a big gain but its better than no cat.
 

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isn't there a sensor around that area also? o2 maybe.
 

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As stated above, that is a bad idea. Leave your CAT alone. If you modify anything, just put on a higher flow muffler, of your choice. The ECM will not run correctly without the sensor on your CAT. It is designed to lower the emmisions, and is also mandatory to have. You will not pass the emissions test on your next inspection without it.
 

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those hi flow cats are pretty expensive too.
 

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Discussion Starter · #10 ·
I don't really see any need to replace the cat anyway. I don't have any problems with it, everything is fine I just know that's what everyone does around here. Thanks for the advice
 

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I on the other hand am a horse of a different color. Depending on the year and make you might be able to remove the cat with no other ill effects then listening to the treehuggers. On my 01 wrangler i took the cat off and put on a flowmaster super 40 muffler. Replaced the cat with a stright pipe of course. The only o2 sensors on my exhaust system are 4 right after the exhaust manifold. 2 before the precats..and 2 after. There was no sensors after the cat or near it. As i said it differs though because my buddies 97 sport has a o2 sensor after the cat and that will cause you to run rich and have your CE light on. But if your set up is like mine it can do nothing but help you. The power increase was extremely noticable in mid range and low end grunt. If you have a header though, it may open up the air flow too much. You have to have at least some backpressure. But ide check out your system to see where the sensors are located. Do what you want to with the jeep, its yours and yours alone.
 

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That is the way mine is set up. Well it sounds like I will be doing away with that cat. Did it make your jeep any louder when you removed it? Im trying to get an idea of what it will sound like. If its too loud I'll just leave it on.
 

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The power increase was extremely noticable in mid range and low end grunt.
Did you dyno it before and after? Or was this more of a seat of the pants kinda thing. Cuz From everything I have read you would maybe gain a couple HP.
 

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Did you dyno it before and after? Or was this more of a seat of the pants kinda thing. Cuz From everything I have read you would maybe gain a couple HP.
I am guessing that it was seat-of-the-pants. I am just trying to figure out if it will be any louder or not.
 

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yes it will be louder. If you want it louder you can also cut the tailpipe a bit. From my experience i installed a flowmaster 50delta on my wrangler and never installed the tailpipe and it was loud enough to shake my seats at idle. I installed the tailpipe which is around 2 ft and few inches and its just a bit louder than stock now.

I also do have a buddy of mine who installed aftermarket headers on his Scion tC on those cars the cat is welded on the header it self so the new header did not have a cat on it and it was loud as hell (it was so loud and crackling). He bought something from ebay which lies to the o2 sensor to make it read "right" so the check engine light doesnt come on. I gotta be honest with you it stinks like crap inside. When he warms up his car he doesnt even want to sit in it since it stinks bad. He did install cat for that reason. If you want to know what it smells like try sniffing the tailpipe when ur jeep is running. Now imagine all that smell inside your car because of traffic lights. If you like it than remove the cat to get those few extra horses (and loose low end torque).
 
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