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Removing the Cat?

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Old Sep 23, 2009 | 05:47 PM
  #1  
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Removing the Cat?

What are the effects of removing the catylitic converter and how do you fix them?
Old Sep 23, 2009 | 06:53 PM
  #2  
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Car: 1987 Pontiac GTA
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Re: Removing the Cat?

You sure you wanna ask that on here? Some of these guy will tear you a knew one for even thinking it because of how illegal it is and all that stuff. I have done it and all i really noticed was a slight loss on mpg and exhaust didn't really get that much louder. How if you want go get one from magnaflow they are built really good and are high flow for about 100 or so.
Old Sep 23, 2009 | 07:35 PM
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Car: 1988 SC Convertible
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Re: Removing the Cat?

Originally Posted by bigpaulz28
What are the effects of removing the catylitic converter and how do you fix them?
The effects- Nothing.

How to fix one? - Take it off the car, with a pipe or piece or re-bar beat the honeycomb filling into small enough pieces so that they'll fit through the opening on each end, and re-install on the car. Take all the pieces from inside the cat to your local recycling yard to get $$$ for your next mod.
Old Sep 23, 2009 | 07:58 PM
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Car: 87 T-Top GTA
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Re: Removing the Cat?

Is there any HP gain? If so, would you get any HP by beating out the honeycomb filling? Or are you more likelly to get some HP with a Magnaflow Cat?

Yes I do know that this is illegal! Unless U use aftermarket Cat! (Right)?

Last edited by y84pauloflondon; Sep 23, 2009 at 08:04 PM.
Old Sep 23, 2009 | 08:02 PM
  #5  
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From: London, Ont, Canada
Car: 87 T-Top GTA
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Re: Removing the Cat?

Originally Posted by bigpaulz28
What are the effects of removing the catylitic converter and how do you fix them?
Why do you want the Cat gone? HP, sound(rumble), or is your Cat falling off?
Old Sep 24, 2009 | 02:57 AM
  #6  
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Re: Removing the Cat?

Having a hollow cat will probably cost you horsepower, as the hot exhaust has to expand into the shell and then shrink back down again to get out. That causes a restriction. It'll also sound "tinny" and "raspy" and be slightly louder.

Yes its totally illegal on a street car in the United States. Its better to replace it with an aftermarket cat. Its been dynoed the difference between a straight pipe and an aftermarket cat, and its about 2-3 horsepower at the wheels. But the difference it makes in the smell and harmful emissions from your exhaust is huge.
Old Sep 24, 2009 | 07:49 PM
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Re: Removing the Cat?

If you have the stock cat now.

Pros:
You will gain a little power (pipe it, don't just gut it)
It will be louder
It will be a bit more throaty

Cons:
It is illegal
Your exhaust smell will be quite a bit stronger and more potent
If your outside near your exhaust there's a very good chance your clothes will smell like it all day. Lol.
Old Sep 24, 2009 | 08:16 PM
  #8  
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Re: Removing the Cat?

Originally Posted by FYRCHKN
The effects- Nothing.
Correction.


Taking it off can......
get you a ticket
cause the inspection station to get investigated and/or fined
result in your registration being revoked
inspection sticker peeled ON THE SPOT
cause you to hafta pay to have it towed home

Need I say more?
Old Sep 24, 2009 | 08:18 PM
  #9  
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Car: 1994 Z28
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Re: Removing the Cat?

Gut it and repipe it... who cares about the environment or state emissions?

Then again, I also have no chance of passing emissions with that carb sitting under the hood of my "tune port injected" iroc.
Old Sep 24, 2009 | 08:19 PM
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Re: Removing the Cat?

simple as what stephen said.... and the car looks sick stephen............
Old Sep 25, 2009 | 11:46 PM
  #11  
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From: London, Ont, Canada
Car: 87 T-Top GTA
Engine: 350 TPI
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Re: Removing the Cat?

Originally Posted by Stephen
Correction.


Taking it off can......
get you a ticket
cause the inspection station to get investigated and/or fined
result in your registration being revoked
inspection sticker peeled ON THE SPOT
cause you to hafta pay to have it towed home

Need I say more?
Keep in mind that i live in canada and our laws are a bit diff. No cat is illegal...but I believe that any car 1987 or older does not need any emissions tests, anything newer will continue to get tested every other year. So really, I don't need to worry about inspections and stuff. (JUST SAYIN').
Old Sep 25, 2009 | 11:52 PM
  #12  
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Re: Removing the Cat?

Originally Posted by y84pauloflondon
Keep in mind that i live in canada and our laws are a bit diff. No cat is illegal...but I believe that any car 1987 or older does not need any emissions tests, anything newer will continue to get tested every other year. So really, I don't need to worry about inspections and stuff. (JUST SAYIN').
After a certain age (depends on the state, mine is 23yrs), we don't have to get an emissions test either, but are not allowed to just start ripping all the emissions stuff off. Visually, we'd still fail, if it was gone.
Old Sep 25, 2009 | 11:55 PM
  #13  
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From: Bertram (outside Austin), TX
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Re: Removing the Cat?

Originally Posted by Badass355ciz28
simple as what stephen said.... and the car looks sick stephen............
Thanks. And I owe my new wide rears to you. (i bought the rear 2 from him) Told ya I was gonna get them widened!

https://www.thirdgen.org/forums/susp...els-315-a.html
Old Sep 26, 2009 | 12:03 AM
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Re: Removing the Cat?

Just get a high flow cat. You will probably get a little different exhaust sound and tone, and probably even gain a little mpg possibly. I cut my cat off my 94 silverado and i really regretted it, because i was making pit stops constantly, that thing lost so much mpg it wasnt funny.

Thats one reason why i havent cut the dual cats off my 91 TA, because people always tell me oh u only lose about a mile to the gallon. BULL****, unless you drive like a super grandma theres no way you milage will be the same. Even though i live in florida and dont have emissions either im still not cutting my cats off, ill replace them for high flows instead of cutting them anytime.

But the plus side.....

It really opened up my exhaust so much better, no more raddling in the cat cause mine was broke, and it sounded a lot more nasty and throaty, i really loved the exhaust sound, but you regret it in the long run once your use to it, and tired of it, and always having to go to the gas station, my truck was stock btw, no mods, that sucker just ate up gas after the cat was cut, and i put on a straight pipe to my flowmaster.
Old Sep 26, 2009 | 01:39 PM
  #15  
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From: London, Ont, Canada
Car: 87 T-Top GTA
Engine: 350 TPI
Transmission: 700R4
Axle/Gears: 3.27
Re: Removing the Cat?

Is there any loss in mpg if using a aftermarket highflow cat? (ex. magnaflow, etc...)

From my understanding is, no loss in mpg and MAYBE a gain of 1-5 HP.(Stock engine, homemade cool air intake, manaflow muffler, belt is off my smog pump. that's all I got right now).

Thankx Guys.
Old Sep 26, 2009 | 03:02 PM
  #16  
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Re: Removing the Cat?

As far as i know you wont really gain more mpg, maybe 1 mile at best with a new one. As far as horsepower, my buddy put a 3 inch magnaflow on his mustang, and he really didnt notice much power gain even dynoed.
Old Sep 26, 2009 | 03:42 PM
  #17  
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Re: Removing the Cat?

In Mass. cars 1995 and older no longer need to pass emissions so i know of people that have taken them off. the question you have to ask yourself is why would you want to. Even though you can cut them it would be better to just add a high flow cat. They don't cut performance whatsoever and it will keep you from getting a hefty ticket if the cops ever look under your car.
Old Sep 26, 2009 | 04:07 PM
  #18  
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Re: Removing the Cat?

Originally Posted by Stephen
Correction.


Taking it off can......
get you a ticket
cause the inspection station to get investigated and/or fined
result in your registration being revoked
inspection sticker peeled ON THE SPOT
cause you to hafta pay to have it towed home

Need I say more?
Bit extreme dont you think?

I've had no cat for like 5 years, no tickets, no problems, not a single shop has denied my inspection, it sounds way better with it off, so thats why I did it.

So what you said is ridiculous and i can guarantee probably will never happen, I've had one ticket in the last 5 years, and that was for "reving my engine/exhaust" right by a cop.

So whoever wants to replace the cat with a pipe, go right ahead, if you get failed on the inspection, go somewhere else tell you pass, simple, cops aren't going to get all dirty trying to look under a car for a cat, at least I've never heard of this happening in my state by any of my friends, or car club ( fastlouis )

As for california people, I'd just leave it on.

And I have no emissions here for pre-96, only visual "safety" inspection.
Old Sep 26, 2009 | 04:34 PM
  #19  
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Re: Removing the Cat?

Bottom Line:

It is illegal. Do it if you wish.
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