91 6Spd. Remove Cats??
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Joined: Oct 2001
Posts: 80
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From: Miami florida
91 6Spd. Remove Cats??
I have a stock 91' 6Spd. which runs like a dream. I live in Miami and we dont have any emission tests here. I went to a local muffler shop (not Midas or Meineke) and the owner (great guy) told me that to remove the cats is a Federal offense and that if I did remove them, my car is going to run very rich (faster). Any thoughts on this??? I dont want to do anything that might lead to problems and I dont see why this guy would talk me out of something that could make him some money.
Thanks
Thanks
Le Mans Master
Joined: May 1999
Posts: 6,517
Likes: 1,304
From: Windermere FL
Re: 91 6Spd. Remove Cats?? (vmaxer)
There is a couple of things I can point out for you. Now I have a 90 auto, so it might be slightly different for you.
The easiest way to do it is to replace the whole system. Or if you want to fight it you could remove the cat and then gut it using a iron pipe. The cat is not easily seperated from the front Y-pipe. The best thing to do is to get a true dual system, like the one MAD sells. That will go straight back from the manifolds to the mufflers. A new set of muffler is :cool:. You can then put back the entire exhaust if you want to. That will also get rid of the pre-cats too. A set of headers will finish the job off nicely.
The only thing that you might be concerned about is the dreaded Code 32 (EGR malfunction) because the EGR needs backpressure to work properly on an L-98. It is hit and miss. Some people get it and some don't. I did. I got rid of them with a nice set of Hooker headers for some reason that I cannot figure out.
The exhaust note is great. It is not load until you go WOT.
I recommend it highly.
You can do it all yourself is you go for an entire system replacement. They you won;t have to fight seperating the rusted, welded components.
The easiest way to do it is to replace the whole system. Or if you want to fight it you could remove the cat and then gut it using a iron pipe. The cat is not easily seperated from the front Y-pipe. The best thing to do is to get a true dual system, like the one MAD sells. That will go straight back from the manifolds to the mufflers. A new set of muffler is :cool:. You can then put back the entire exhaust if you want to. That will also get rid of the pre-cats too. A set of headers will finish the job off nicely.
The only thing that you might be concerned about is the dreaded Code 32 (EGR malfunction) because the EGR needs backpressure to work properly on an L-98. It is hit and miss. Some people get it and some don't. I did. I got rid of them with a nice set of Hooker headers for some reason that I cannot figure out.
The exhaust note is great. It is not load until you go WOT.
I recommend it highly.
You can do it all yourself is you go for an entire system replacement. They you won;t have to fight seperating the rusted, welded components.
Melting Slicks
Joined: Aug 2000
Posts: 2,009
Likes: 1
From: Springfield MO
Re: 91 6Spd. Remove Cats?? (Flame Red)
I gutted them on my 90. No codes and no problems. It does smell a bit more like exhaust, but no complaints. Mine were busted and causing a knocking noise so I figured why not get get rid of them. In MO. you wouldn't find very many muffler shops that will eliminate the cats.
Team Owner
Joined: Aug 2000
Posts: 42,935
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From: Sydney, Australia
CI 6-7-8-9-10 Veteran
St. Jude Donor '07-'08-'09-'10-'11-'12-'13-'14-'15-'16-‘17, '22
Re: 91 6Spd. Remove Cats?? (vmaxer)
Finding a muffler shop to do the work may be the biggest hassle.
The computer in your car is able to compensate for minor changes made to the motor (intake, exhaust). If the O2 sensor dedects a lean or rich condition it will adjust the injector pulse width (firing time) and ignition to compensate and keep the fuel to air mixture at its optimum. You don't need a new chip if you open up the exhaust and/or intake a little (unless you trip the dreaded code 32 in the MAP equipped L98's and the SES light bothers you (90-91 models)). The code 32 causes no harm, it is an annoyance more than anything else as it causes the service engine soon light to come on after constant cruising.
You will notice a difference in performance, I know without precats (the two at the front) you will notice a difference and if you hollow out or remove the centre cat you will gain even more. Noise will increase though but whether this is an issue is up to you.
Bottom line: You will get an increase in performance, you will get more noise, & your air fuel ratio should be fine BUT you might get into a little or lot of trouble if the EPA (or whatever department is responsible for emissions over there) finds out.
HTH
The computer in your car is able to compensate for minor changes made to the motor (intake, exhaust). If the O2 sensor dedects a lean or rich condition it will adjust the injector pulse width (firing time) and ignition to compensate and keep the fuel to air mixture at its optimum. You don't need a new chip if you open up the exhaust and/or intake a little (unless you trip the dreaded code 32 in the MAP equipped L98's and the SES light bothers you (90-91 models)). The code 32 causes no harm, it is an annoyance more than anything else as it causes the service engine soon light to come on after constant cruising.
You will notice a difference in performance, I know without precats (the two at the front) you will notice a difference and if you hollow out or remove the centre cat you will gain even more. Noise will increase though but whether this is an issue is up to you.
Bottom line: You will get an increase in performance, you will get more noise, & your air fuel ratio should be fine BUT you might get into a little or lot of trouble if the EPA (or whatever department is responsible for emissions over there) finds out.
HTH
Instructor
Joined: Jun 2001
Posts: 116
Likes: 0
From: Ft. Worth TX
Re: 91 6Spd. Remove Cats?? (vmaxer)
I gutted mine about a year ago. I couldnt get to the pre-cats, but I gutted the main cat. Then about a month later my pre-cats gutted themselves. Dont ask me how. I think the increased air flow blew them out. As for a performance gain. It felt like about 15-20 hp. And it sounds awesome. I get a couple of codes, but nothing to worry about. I would say do it...
