Cat Delete??
Thread Starter
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Joined: Feb 2012
Posts: 95
Likes: 1
From: Valparaiso Indiana
Cat Delete??
I was thinking about just completely taking off my cat and replacing it with a straight pipe in hope of a louder/deeper tone. I could really use some opinions on this, the pros and cons. Any error codes, hp or tq loss? Please let me know. (85 corvette)
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
The O2 sensor is long before the cat, so there is not a problem with that. The removal with not set any error codes. The 85 cat bolts in and out so it is easy to remove for the straight thru pipe. I do this when I take the car to the track. The 85 is choked with the cat and exhaust system. I gained 1/2 second in the quarter mile when I installed the straight thru pipe for the cat and added the March under-drive pulleys.
I didn't really notice any change it exhaust tone. You will GAIN HP and Torque. I built my own straight thru pipe using the flanges off the old cat when I installed a new Magnaflow cat.
I didn't really notice any change it exhaust tone. You will GAIN HP and Torque. I built my own straight thru pipe using the flanges off the old cat when I installed a new Magnaflow cat.
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Joined: Aug 2011
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http://www.corvettecentralexhaust.co...mance_dual.php
i bought the set with the LT1 Mufflers in march, the tone is great and so much happier without the cat. has a spot for the o2 sensor as well.
i bought the set with the LT1 Mufflers in march, the tone is great and so much happier without the cat. has a spot for the o2 sensor as well.
Race Director
Joined: May 2006
Posts: 10,691
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From: Phoenix Arizona
The exhaust will usually be quite a bit louder/deeper with stock mufflers, especially at idle. Non track performance will be about the same (unless the cat is plugged), though you might think it's faster because of the increased noise. Gas mileage will be about the same again barring a bad cat. OBD1 cars do not monitor exhaust past the cats (94's and 95's do but won't set the SEL light.) Over the years there has been a lot of threads about this.
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Joined: Feb 2012
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From: Valparaiso Indiana
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Advanced
Joined: Aug 2011
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you could either leave them there, get a new Y pipe w/o the precats and make a straight pipe like John did, or get an exhaust system similar to the one i posted
i honestly dont know how much the precats will affect the tone/volume of your exhaust, i assume it would, i just honestly dont know
i honestly dont know how much the precats will affect the tone/volume of your exhaust, i assume it would, i just honestly dont know
Burning Brakes
Joined: May 2004
Posts: 1,201
Likes: 2
From: Frederick Md
My 88 is a cruiser.. definitely not a race car...
I just put on muffler eliminators ..sounds a lot better without any mufflers..
Bob G.
66 72 and 98 Convertibles
76 79 and the 35th ANC coupes
I just put on muffler eliminators ..sounds a lot better without any mufflers..
Bob G.
66 72 and 98 Convertibles
76 79 and the 35th ANC coupes
Drifting
Joined: Mar 2006
Posts: 1,263
Likes: 188
From: Wabasha Mn
If you can find a muffler shop that will do a true dual exhaust system it really does not take much. My exhaust guy cut out the "Y" portion in the head pipes and after the cat and welded in new pipes to make the dual exhaust. You can also buy the true dual kit at Corvette Central and some of the other shops for $300. My exhaust guy charged me $300 to do it but with true duals and not cats you can feel the difference. The factory stainless steel shorty headers are pretty efficient also.
Instructor
Joined: Jan 2006
Posts: 158
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From: Norco California
Years ago I put some short straight thru (cat back system ) mufflers on my 86 thinking it would sound nice.It really made no difference. Fast forward to a couple of years ago I replaced the original and worn out cat with a new highflow cat,and wow what a difference in sound,way louder and sounds good.Couldn't eliminate the cat as I am in Cali and must still smog test the car (which always passes no problem)
Team Owner
Joined: Mar 2012
Posts: 27,118
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From: Montgomery, Alabama
2017 C6 of Year Finalist
Replaced the cats on my 92 with straight pipe. The sound is definitely louder and deeper.
May be a little bitty too much at WOT though. I had to hit it and it really vibrated off the azzoles car that I passed. He was doing 35 in a 55 and deserved it.
May be a little bitty too much at WOT though. I had to hit it and it really vibrated off the azzoles car that I passed. He was doing 35 in a 55 and deserved it.
Race Director
Joined: May 2006
Posts: 10,691
Likes: 71
From: Phoenix Arizona
It is illegal for any shop to remove cats (seems like its a $10k fine). Any Fuel injected 85 will not pass a "sniffer test" wihout a cat. And any carburated one won't pass the visual, at least by the book, yeah, I realise no 85's came from the factory with carburators. If you don't have to worry about emmissions, due to the age of the car, it probably wouldn't be an issue on resale. If they are worried about saving the planet, they probably aren't buying used vettes).
Last edited by zr1fred; Aug 14, 2012 at 07:35 PM.
Safety Car
Joined: Aug 2009
Posts: 3,751
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From: Melbourne, Victoria, Australia
You may be pleasantly surprised to find your cat is hollow inside
That is what i found when i had the exhaust off, was planning to ram a two and a half inch pipe thru it. Was kind of disappointed the cat had no guts in it for me to have my way with.
You will not get any codes
Am sure you can get hi flow cats if you have to pass annual smog tests.
That is what i found when i had the exhaust off, was planning to ram a two and a half inch pipe thru it. Was kind of disappointed the cat had no guts in it for me to have my way with.
You will not get any codes
Am sure you can get hi flow cats if you have to pass annual smog tests.
