catalytic converter
Melting Slicks
Joined: Oct 2008
Posts: 2,946
Likes: 55
From: b.b. n.j.
Race Director
Joined: May 2006
Posts: 10,691
Likes: 71
From: Phoenix Arizona
There will be no codes, the 85 does not monitor after the cat. There will be more noise (about 40%). There will be no change in fuel economy or performance unless the old one is plugged. There should be no large increase in smell. There is really no advantage to doing it, and it will affect resale if you live in or near to a monitored area.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Your 85 has a pair of "pre-cats" in each side of the front Y-pipe. There is also a "main cat" where the front Y-pipe connects to the single exhaust pipe leading to the rear Y-pipe.
You don't mention where you live or if you have to have an emissions test for plate renewals so that may be a factor in your decision.
As mentioned, you may not see a lot of increase in power if you simply remove the three cats. There are replacement front Y-pipes available without the pre-cats and it's not hard to fab up a pipe to replace the main cat. There won't be a code set so no SES light will come on.
But most muffler shops will refuse to remove any working cat from a car. The federal gubbmint can levy a huge fine (5 figures
) if a shop is caught doing that without replacing a defective unit.
You would be better off with true duals and a pair of free-flowing mufflers to pick up a few HP. The various catalogs have true dual exhaust pipes that bolt in and accept the stock mufflers or aftermarket ones made for C4's.
You don't mention where you live or if you have to have an emissions test for plate renewals so that may be a factor in your decision.
As mentioned, you may not see a lot of increase in power if you simply remove the three cats. There are replacement front Y-pipes available without the pre-cats and it's not hard to fab up a pipe to replace the main cat. There won't be a code set so no SES light will come on.
But most muffler shops will refuse to remove any working cat from a car. The federal gubbmint can levy a huge fine (5 figures
) if a shop is caught doing that without replacing a defective unit.You would be better off with true duals and a pair of free-flowing mufflers to pick up a few HP. The various catalogs have true dual exhaust pipes that bolt in and accept the stock mufflers or aftermarket ones made for C4's.
Safety Car
Joined: Oct 2008
Posts: 4,689
Likes: 4
From: Yucaipa CA
Your 85 has a pair of "pre-cats" in each side of the front Y-pipe. There is also a "main cat" where the front Y-pipe connects to the single exhaust pipe leading to the rear Y-pipe.
You don't mention where you live or if you have to have an emissions test for plate renewals so that may be a factor in your decision.
As mentioned, you may not see a lot of increase in power if you simply remove the three cats. There are replacement front Y-pipes available without the pre-cats and it's not hard to fab up a pipe to replace the main cat. There won't be a code set so no SES light will come on.
But most muffler shops will refuse to remove any working cat from a car. The federal gubbmint can levy a huge fine (5 figures ) if a shop is caught doing that without replacing a defective unit.
You would be better off with true duals and a pair of free-flowing mufflers to pick up a few HP. The various catalogs have true dual exhaust pipes that bolt in and accept the stock mufflers or aftermarket ones made for C4's.
You don't mention where you live or if you have to have an emissions test for plate renewals so that may be a factor in your decision.
As mentioned, you may not see a lot of increase in power if you simply remove the three cats. There are replacement front Y-pipes available without the pre-cats and it's not hard to fab up a pipe to replace the main cat. There won't be a code set so no SES light will come on.
But most muffler shops will refuse to remove any working cat from a car. The federal gubbmint can levy a huge fine (5 figures
) if a shop is caught doing that without replacing a defective unit.You would be better off with true duals and a pair of free-flowing mufflers to pick up a few HP. The various catalogs have true dual exhaust pipes that bolt in and accept the stock mufflers or aftermarket ones made for C4's.
Racer
Joined: Jun 2009
Posts: 429
Likes: 0
From: Marlborough CT
I removed my cats in my 85. It definitely has a better sound to it then before. My check engine light does come on every once in a while, which I thought was because of the missing cat. Guess i'll have to check into it. Performance was there was no notable difference. No difference in smell either.
Melting Slicks
Joined: Feb 2005
Posts: 2,057
Likes: 5
From: Bay Shore, NY
no pre-cats in the 84 or 85 front y-pipe.You won't see any performance gains really. You will get a louder exhaust note and if you have an automatic you may notice that the low end torque that was there before has moved further up the power band so it will seem the car has lost some power.
As far as setting the CEL, I had gutted a cat on an 87 Firebird and it never once set the light in the 8 years I owned the car so I doubt your car would set it off. If you don't care or need to care about emissions, you can just gut what you have and re-install the empty shell. It will look like there's a cat there in case a visible inspection is needed for inspection, etc.
If your cat has gone south on the other hand and you still need to pass emissions, pick up a cheap direct fit from eBay or Rock Auto, should run you about $100. The cats on the 84 & 85 bolt in to the front and rear y-pipes with 4 bolts on each. If you still have the original on your car, I can guarantee that will have to put a torch or something to the front bolts to loosen them and get it off.
Depending on your local laws, if you remove the cat completely you may not be able to pass vehicle inspection even if your car is emission exempt so check that out.
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