Have a '90 with relatively low mileage that's been great so far, but I've been staring at rust on my exhaust manifolds and convincing myself it was the source of exhaust leakage and that I should look into headers as a solution. For reference, at some point the previous owner of the truck replaced the exhaust from the cat back to mostly straight pipe into a glasspack style muffler, and it still looks like new.

Took the truck to a muffler shop, who said they didn't do anything with the manifolds, and referenced me to a mechanic close by. That mechanic does a good bit of hot rod style work, and after taking a look said the leak was from the cat being blown out from age, and that headers wouldn't be worth the time or $. He referenced me back to the muffler shop and said the best route would be just to have them delete the cat (truck's old enough for no emissions test here in GA), which would do just as good of a job of eliminating the unnecessary backpressure and would get me the sound and power bump I'm looking for.

That sounds logical, but I wanted to ask the forum for thoughts before I take it back to a muffler shop and let them spend my money. Will I run into any issues deleting it with O2 sensors or anything else related? I'm not concerned so much about the emissions aspect, I really just want the entire exhaust system to match what got replaced, lessen the rust concerns, and overall know that the exhaust is free flowing and giving me at least some nicer noise and performance.

 

Your check engine light will be coming on; and your computer won't be able to meter the gas properly without an O2 sensor.
It may be cheaper in the long run to buy a y pipe with the cat and then you'll have newer exhaust front to back.
And even though older trucks don't have to go for an e-test it's still illegal to delete emissions equipment - very hefty fine attached.
While it's unlikely you'll get caught, it happens.

 

I guess that would explain the vague response I got from the two muffler shops I called about removing the cat then. Looking up replacement cats, looks like a Y-pipe is part of the deal, or am I looking at something different?

I guess that brings me back to still thinking of headers in order to get better flow and sound if I need to keep a cat in place....

 

You won't have a CEL by deleting the CAT on your '90, but your exhaust will smell extremely rich.

 

Without a cat your tailpipe will emit carbon monoxide instead of carbon dioxide. If you read up on the difference you'll see why you have a cat in the first place.

 

I know I get called a tree hugger and folks get extremely upset at me saying this (not sure why, it's just an opinion), but in my opinion.........based on my own experience with my truck, just replace the cat with a new one and be done with it. You should be good for at least 150K unless your truck is burning oil.

My truck (a '90) had an extremely rich exhaust smell with the old cat. After replacing everything else that could possibly make it run rich, that extremely rich smell finally went away after replacing the cat.

I have heard that on the Mass Air trucks, you can get it tuned so that it doesn't have that rich smell without the cats.

Just my .02.

 

I don't know if this is still an option, but in the past, I have had just theta replaced without changing the whole pipe. There was a shop around that did nothing but replace cats.

 

After a few more calls I finally reached a guy with a speed shop a little outside of the city who was very helpful. He wanted to make sure that the rust on the manifold wasn't too rusted before committing to an estimate, but he basically quoted for getting shorties on, and getting new pipe routed to where the newer rust free pipe I already have begins.

The drive out there will be a little bit of a pain to work into the work schedule, but at least seems like the honest info and pricing will be worth it. Thanks to all who's weighed in on the thread so far, it's helped me learn!

 

I have an 89 302 and was going to go catless with long tube headers and dual exhaust.Should I run 2 cats or can I go without? Thanks. Jim

 

make sure you keep an o2 sensor, truck will run like garbage without it