thoughts about Cat converter on 2003 grand prix

[Badgers4life]

So I was looking into some exhaust mods and a bunch of guys had recommended just gutting out the cat converter. This would definitely give me more flow through the exhaust and I dont have to pass any emissions testing. I also know that my 2nd o2 sensor will probs throw on a check engine light, but I dont think anything should be affected. Thoughts?

 

[Fivefingerdeathpunch]

Leave it alone, you wont gain anything by removing the cat/gutting it.

All 01+ cars run a cat diag in the PCM aswell, so if one were to remove the cat the rear o2 will pop a code and ruin your gas mileage as it trys to make the rear o2 happy by adding more fuel.

 

[Badgers4life]

Any other opinions?? I have had a lot of people tell me that the basic principle "more air in, more air out" is the best way to go and I know gutting the cat will let a heck more out (at least less resistance).

 

[OH4CompG]

Any other opinions?? I have had a lot of people tell me that the basic principle "more air in, more air out" is the best way to go and I know gutting the cat will let a heck more out (at least less resistance).

The stock cats aren't restrictive. i know someone that ran 12.3's with a stock cat and 3" in and 3" out tubing.

 

[dpzelenak]

if you want you can use some headers, but if not. Buy a catted DP that well delete the u-bend and maybe replace the res with an aftermarket one

 

[Jcinstalls]

I have a 3100 with a stock cat, res, and ubend delete. I just took the stock stuff to a muffler shop and welded in a magna flow res and o2 bung in place of it. ( the bung is just for a air/ fuel sensor and the rear o2 sensor has a o2 emulator pluged in) And at the end of the pipe is a magnaflow free flow muff. To be honest it is louder than i wanted but sounds good. It also is all ceramic coated and wraped in that fiberglass wrap to quiet it down even more. I say do it! With higher quality res and muff, like an actual sound canceling muff and res. especially if you have an audio system it would cancel out mid bass frequences around like 150- 300 hz. didn't notice and hp gain but it sure looks cool! Tune your exhaust, have some fun!