2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Cutting of Cats

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Old Feb 4, 2014 | 06:27 PM
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Cutting of Cats

Well I may sound dumb for posting this but i couldnt find anything about it. I am very tight on funds at the moment so i want to cut the cats off of my FC and weld in a straight pipe. I have heard good and bad. The good is of course slight hp gains, the bad was that since you lose back pressure the car doesnt want to start. I have no idea. Any help would be greatly appreciated. Thanks.
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Old Feb 4, 2014 | 07:46 PM
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How is cutting the cats going to fix your financial situation?
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Old Feb 4, 2014 | 07:53 PM
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roTAR needz fundZ
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Originally Posted by PaperNinjaRotor
Well I may sound dumb for posting this but i couldnt find anything about it. I am very tight on funds at the moment so i want to cut the cats off of my FC and weld in a straight pipe. I have heard good and bad. The good is of course slight hp gains, the bad was that since you lose back pressure the car doesnt want to start. I have no idea. Any help would be greatly appreciated. Thanks.
Depending on what car you have, if you got a diesel than ya, cutting the cats not a good idea

Now since i'm guessing a rx7, i got a 88 n/a with a r/b header straight back into magna flows, and i have ZERO problems starting, even with it being below 20F, takes about 2 revolutions and fires right up
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Old Feb 4, 2014 | 09:13 PM
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Slight hp gains until i get the money to buy the racing beat exhaust kit i want! the financial problem is being a college student, and nothing is gonna fix that
But thank you for clearing that up.
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Old Feb 4, 2014 | 09:33 PM
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Originally Posted by PaperNinjaRotor
Slight hp gains until i get the money to buy the racing beat exhaust kit i want! the financial problem is being a college student, and nothing is gonna fix that
But thank you for clearing that up.
OK, but you are proposing something that will cost time and money. It isn't a good idea to go forward with this project unless the cats are so clogged that they are severely affecting gas mileage. Anyway, as mentioned above, it has zero effect on starting.
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Old Feb 5, 2014 | 06:22 AM
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What all goes along with removing the air pump?
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Old Feb 5, 2014 | 10:31 AM
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Originally Posted by PaperNinjaRotor
What all goes along with removing the air pump?
Things not working that you need to work?

I hate to say it, but you seem hell bent on ******* the car up when you don't have the money to fix it.
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Old Feb 5, 2014 | 10:41 AM
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go buy a civic and put some taillights on it man, give this car to someone who will appreciate it
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Old Feb 5, 2014 | 12:38 PM
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maybe he's trying to sell the OEM cat for cash to the recyclers. sort of like selling a kidney to the black market.

the no start issue is news to me, but new stories pop up every year so i shouldn't be surprised.
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Old Feb 5, 2014 | 01:59 PM
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Originally Posted by PaperNinjaRotor
What all goes along with removing the air pump?
Can't pass emissions under ANY circumstance, water pump slippage, no pressure source to activate the 5th/6th ports without using exhaust [exhaust activation is super unreliable].
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Old Feb 5, 2014 | 02:32 PM
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it's been about 10 years since i started saying this but it still holds true for most anyone. if you have a stock engine you are better off leaving all the emissions equipment in place. only a turbo engine has any real benefit from removing them.

if your cat is dying or dead just have it replaced, this usually costs no more than $200 and you won't smell like a dirty hooker at a gas station when you drive. if you want to remove it and deal with the auxiliary ports and an activation system for maybe a 10horsepower increase(if you actually follow through with a proper auxiliary port activation device), have fun with that.

in all my time working on these cars the non turbos that perform the best are usually the ones where no one has been ******* around in the engine bay. it's almost a pleasure driving a 100% stock car that doesn't smell like raw gas, is loud as a banshee and feels like i'm crawling because the noise still doesn't give me an impression of a faster speed... the non turbo stock engine cars run best all around with a somewhat restrictive exhaust system. i drove a non turbo s5 recently with a dual header into a single 3" mid-car and i was unimpressed, it was slower than a stock s4 non turbo car(not to mention it sounded like a hornet stuck in my ear), maybe the nitrous will wake it up..

Last edited by RotaryEvolution; Feb 5, 2014 at 02:44 PM.
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Old Feb 5, 2014 | 03:19 PM
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Yea my ol s4 n/a liked a lil back pressure and the 5th/6th ports working
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Old Feb 5, 2014 | 05:33 PM
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Damn, didnt mean to offend, and I do appreciate it, its my second one, my first one got slammed by an 18 wheeler that didnt give a f*** and ran a light, my bad though

Last edited by misterstyx69; Feb 7, 2014 at 10:42 PM.
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Old Feb 5, 2014 | 06:11 PM
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well if you give a reason for removing it that may help your cause. if it's just to free up some power then you will have to consider consequences as power usually doesn't come free and requires tweaking something else in the process.
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