I have an 89 GTA with 5.7 and an auto. I am thinking about dumping the dual cats and switching to a single cat. i dont think that i can do this is CA but I wanted to know if anyone has done it and gotten away with it.

Brian

 

why would you want to ditch them

 

Hey. Yeah it can be done. I did it cause single cat parts are cheaper. But if I remember right it is illegal cause you're not supposed to alter the number of cats on a car. I suppose if you didn't have visual inspections and you passed then no one would be the wiser.

My 2 cents,
David

 

I think it's legal since it was a dealer option.

 

Call up your local smog referee and ask them. http://dmv.ca.gov/ might also have some info.

And yah, why would you want to do that? Two pipes are better than one.

 

I want to do this because if I buy two high flow cats it is like $300. If I only have to buy one it is only like $150. That leaves me $150 to spend on something else.

Thanks for the help
Brian

 

I would straight pipe both those cats if you thought you could still pass emissions check

 

You've never been to California, have you, Rich?

Keep the dual cats. You'll have to spend more than just the money to buy the single cat, since you'll have to merge the two pipes before the cat, and reattach the cat-back some other way after it. It may end up costing you more, in fact.

Besides, the dual cats are worth 10-15 HP. You'd have trouble bettering that with some other mod for $150.

 

You could also just gut them and leave them there. Most cars with gutted cats still pass emissions just fine.. I did!

 

well now this is a great thing alot of people disagree with me but they make stuff you pour into your oil. This is a 2 for 1 deal this stuff increases oil pressure and will help you pass your emission test. I don't know how but I have a friend in CA and he did it and passed, there are many different brands but you can find it at Advance auto parts just look in the gas/oil additives area

 

keep the two cats and go to a shop that sells them at a reasonable price.

when i had my cats done, i went to a local performance shop here in sacramento CA (muffler tech). They set me up with two 2.5" catco hi flow cats, the step up/step down adapters (since stock pipe is 2.25") all installed professionally and clean, out the door for right around $220.

works great, and the cats are slightly bigger than the pipe to help ensure they aren't a restriction. i really can't see any reason to spend the same amount of money on a single expensive converter, and i can't imagine a single expensive converter (even a random tech) outflowing a pair of 2.5" catco's. you were blessed with dual cats, keep them!