I'm thinking about knocking out my cats. (removing the insides) Has anyone done this on a stock GT? I'm worried about setting codes.

 

if you gut the cats, you're gonna trip codes. no doubt about it.
why not install high flow cats instead? keep it street legal.
the cats that come on it are high flow to begin with but there are aftermarkets that have slightly better flow.

 

Go ahead and do it and then tell if it works well on gaining more horsepower?

 

I'm looking for sound at the moment, not hp.

 

You do realize that high flow cats are not legal. Technically, buy the letter of the law, any modification what so ever to the factory exhaust system makes it an illegal exhaust system. This includes high flow cats, relocating cats, headers, X pipe, anything.

 

I have done it on a 05 Gt and didn't have any problems. You do not have to put a tune on the car. It does make your exhaust louder and it sounds good!

 

Thanks Royboy, I guess what some people here are not thinking about is, If you knock them out, the dealer thinks your car is still stock! And yes you will gain HPs. I did it on my old 88 GT and it made a big sound and HP gain, but I was not sure if it would trip codes on the new 07s.

 

This seems odd to me. I figured you would get a check engine light with a code for insufficient catalyst. Wouldn't you need to turn off the after-cat O2 sensors? I don't believe it would hurt the car to have gutted cats, but I would hope my car would show a check engine light if I had a flow problem with my cats.

 

If your going to gut your cats.. make sure you spend a good 10 minutes using a high pressure air blower to blow them out before you put them back on your car.

I did that to my Eclipse, and some debris got into my muffler, and made a bunch of clanking noises. Also i saw 0 gains from doing it to that car.

 

I was told that the 07 comes with high flow cats so how are they illegal.