Hey guys. I have an Alta single exhaust on my 03 S. I was glad that it came with the car.

(( For the impatient types; here's the question: If i eliminate the CAT or Empty it out, will it throw a code on this car? (some cars don't, some do.. would be nice to know, BEFORE I do it.).. For people who have a few minutes to read, and don't mind, please continue. ))


It has the stock manifold, and the thing is, i can't really tell without taking the exhaust off, whether it's the stock cat, or a high flow that came with the Alta setup... They don't make this particular exhaust anymore so google comes up kind of short. it's a large round tube that looks almost exactly like the Alta muffler, no weird shielding, it's not hexagonal like some are, and all of the tube is the same size throughout, so i just assume it's a manifold-back exhaust. not a cat back. What i mean is, most cats i see are more "ornate" than just a long metal tube. but.. it could go either way.

Anyway, the question isn't (necessarily) whether my cat is stock, or if it came with the Alta exhaust, but, more on the technical side.

---> Will my car throw a code if:::::

On about half of the cars i've owned, (I have modded/souped up/altered/customized every car i've owned) if i :
1) ran a piece of tube in place of the cat / swapped with a high flow
2) emptied out the existing cat to get better flow

I've ended up getting check engine lights and thrown codes. BUT on just any LS1 car I've owned (8 of them actually), i have had NO issues at all, as long as i left all of the 02 sensors where they go or welded in new bungs (depending on what I'm doing).

I need to know, before i take extreme measures, whether this car will throw a code if i empty / kill the cat, assuming that the one i have, is stock. If it's the stock cat, and i empty it out, then get a code, i'll have to buy another one. That's just not in my vocabulary.

If i take it off and see that it's a high flow, i'll just leave it alone. otherwise, i'm going to open it up. I'm also going to chop open the Alta muffler and take some of the baffling out of it, and may even shorten it a few inches and extend the pipe so the tips still align correctly. It's just not aggressive enough for me, and i don't want to build a custom from scratch when i already have a decent setup to work with.

Thanks guys!

 

Any alteration to either cat will leave you with a CEL. There is no way around it short of tuning the car and removing the secondary o2 sensor.

 

Awesome thanks. Glad i asked first. I suspected as much, but it's always good to verify. I'll just partially de-baffle the alta muffler, it should be plenty loud.