i have an 89 iroc and it has about 45000 miles on it. so that means it is almost time to change the cats. I read that if you have an 89 or older camaro you have the two cat system. Well i only have the single cat. dont know why but is it illegal to go to the twin system when i change them??

 

most tpi cars came with a single 3inch cat unless the dual cat option was picked up. unless your cat is clogged, falling apart, or you failed emissions, there is no reason to replace it.
if you are worried about teh letter of teh laww you can install a dual cat set up as long as it uses teh factory location for the cats to be hung. fed highway law says you can not alter the number or position of the cats on a car, but there is a provision that allows factory alternative set ups, which is what the dual cat was.

later
tim

 

Also since the dual cat setup was a factory option not indicated by the VIN#, there shouldn't be any way for the emissions people to tell if your car is supposed to have it or not. They'll most likely just look under the car, see the cats, and be happy.

 

Cats just restrict exhaust flow, who needs them. I've took them off of both cars that I own. A '84 Monte Carlo SS and a '91 Camaro convertible. I had a friend who had his emissions checked before and after taking off his cat and it put out cleaner emissions without it on. It's a dumb law that stupid politicians and the EPA pushed just to make themselves think they are doing something good without ever doing the necessary research

 

lmfao, lack of research uh? a good cat will cut down on harmful pollutants. they DO help. with that said, i dont run one and if you like a performance sound i suggest you dont look at em...

 

The only way removing a cat can clean up your exhaust is if the cat is clogged or severly damaged. I mean, after all, cleaning the exhaust is the whole POINT of a catalytic convertor.

BTW I don't have one either, strictly for performance reasons.

 

I had a 92Z with the dual cats cut off. I thought it sounded like ****. I didn't run any times before I cut them out so I don't know how much removing them helped.

 

We're not living in the "pancake-style-converters" days anymore. With the curent technology, the "High-Flow" cats are extremely efficient and low back pressure. I saw NO increase in my 1/4 mile times from running "empty" stock converters, to running high flow units. It really didn't make a big difference at "E-check" either, I "fast-passed" with empty ones and so did my friends'.
I ran mine w/o a muffler, just cats and pipes, and it was plenty loud like "glass-packs"and straight pipes. I think the muffler design and mounting location have more to do with the sound than the cats. I'm sure they quieten it a little, but I think it's a very little.
This whole Emissions Campaigne shouldn't really be aimed at us anyways.
B/C we know... "If it don't run clean, it don't run FAST!"...

 

Yes, the latest research shows that a high performance 3" cat will only cost you 3 to 5 hp. That ain't even noticeable.