I've got a 1989 IROC with the G92 package which includes dual cats. The previous owner replaced the muffler and dual tailpipes with some kind of muffler-less "Corvette" pipes. I think the tailpipes are fiberglass-filled or something.

I would like to go back to a more traditional exhaust and my question is can I buy any one of the various aftermarket cat-back systems and bolt them behind my existing dual cats? Will it require some fabrication of the system to fit or is the outlet of the dual-cat system in the exact same spot as on the more common single-cat system?

The system is still original from the stock exhaust manifolds back to where the original muffler was located. It's got some noticeable surface rust on the y-pipe. Would it be better to replace the original dual-cats and y-pipe with a new y-pipe and single 3" cat or should I grind the rust off and keep the original y-pipe and dual cats. Replacing the stock dual cats is more expensive to do and I thought I would throw that out to the boards for an opinion.

Thanks,
Matt

 

Two pipes flowing thru two cats is going to be better than one pipe flowing thru one cat. Dual cats is worth it. Why do you think dual exhaust is so popular?

And nothing aftermarket is a direct bolt on. Expect to do a little fabricating.

 

look for setups that are sold specifically for your model... as previous post stated you will have some minor mods, but it will be far less than if you go the good ol' fabricate as you go..

 

I always thought the aftermarket cat-back kits were a direct bolt-on and required no cutting, but I have never installed one. As long as the kits include enough piping to fit, then a little cutting is not a problem.

Do you think the original 21-year-old cats should be replaced or do they hold up well enough? The car has 170,000 miles on the clock.

Thanks.

 

I would say replace them, but others here, say don't replace them.... my logic is that you don't know how the previous owner maintained the vehicle, whether he drove around leaving the SES light on, alerting him of a faulty O2 sensor, you just don't know... and especially since it's emissions related hardware, I'd say replace it...

 

I have an 89 RS and I changed my cat last year when I got it. It was original and the honeycomb inside was broken apart in so many pieces. Get a couple high flows. I know you want to save money, but it will be worth it and they will last just as long or longer.