# Exhaust/Cat question



## r3d04gto (Jan 3, 2011)

*waves*

Hey all, pretty new here. I've actually owned an '04 GTO for about a year now but just found this place a few hours ago. I wanted to ask some fellow owners for some opinions and knowledge. My usual mechanic said he wasn't *entirely* sure (although he could find out for me) because he's only ever worked on half a dozen GTOs. Basically I'd like to do some exhaust work as follows...

I'd like to delete two of the four catalytic converters. Not sure why there are four, but two seems to be more than enough and the flow with only two would be much, much improved. Will that set off any check engine lights? I know some cars do, some cars don't. Needs to still pass inspection/emissions.

Now either way, would buying high flow cats be worth the extra money? Is it a noticeable difference?

And finally... for an actual exhaust... I bought it with just some Flowmaster mufflers thrown on. It's not a bad sound, but I'd like to do more. What would be more worth it: buying a system like a Magnaflow/Flowmaster/Whatever, or picking up some nice sounding mufflers and getting some custom pipes done by a shop? I actually like the sound of the Corsa Sport the best, but I think the singular exiting pipe looks dumb as all get out. Looks like it fell off a Honda, honestly.

Thanks in advance!


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## GM4life (Mar 18, 2007)

'04 GTO's only have two cats, nearest to the engine between the two O2 sensors. The resonators are behind the rearest O2 sensors, they are mounted directly to the tranny.


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## Noob1986 (Jan 9, 2010)

I believe that there are two Cats two resonators and two mufflers in the stock exhaust system. You can get rid off everything except the cats without tripping an o2 sensor. High flow cats are definitely worth it if your interested in sound, and squeezing every single horsepower out of your exhaust system. My only concern is that you would be modding piping that you are most likely going to replace with an aftermarket catback system. As for the Corsa system, i would agree with you if you were talking about the circular tip, but the oval tip, i think, looks much better than trying to squeeze two small diameter pipes out that small exit point in the back. Another idea would be to get the 05-06 corsa and swap rear bumpers with an 05 or 06 gto. I had a buddy that did this and it looked great.
Here's _my_ corsa exhaust with the oval tip... i like it


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