So i have been told something different from every shop i've talked to now and am getting a little fed up...

So some shops have told me that i wont need to buy a new catalytic converter
Others say they will inspect it and see
And the rest tell me i will HAVE to have a new one

So for anyone who has done an exhaust system if you could give me your two cents on the matter it would be really appreciated:)


car is in perfect running shape, and has 90xxx miles on it...

Hey man, are you talking about your top or bottom cat? I'm guessing your talking about the bottom since you want an exhuast. You shouldn't need it, they'll just have to add a bung for your second O2 sensor on the pipe after that area. Honestly you're not going to see any gains from removing it, I would just recommend getting a high flow cat for down there to help gaurantee that your second O2 sensor receives the correct readings and maintain legal emissions. Of course you could just have them make a delete pipe for you that way you can add a cat later to pass emissions and then remove it again easily. They have to add that bung for the sensor after that section anyway.

I think it depends on what size piping you are getting as well. For example, if you get a 3" pipe, I don't think they will be able to use your old cat because the inlet/outlet is alot smaller. You of course dont have to have one though. Just keep in mind that if your state is strict like mine (california) you will never pass smog with anything other than what is already there.

Unless you have a turbo, 3" is a little overkill.

Well i am planning on running 2.25 pipes...

So basically what i am gathering that if i do get a new one it should be a high flow cat?

What would be the gain to not having a cat? It seems like alot of work to deal with to not have one...

Honestly there have been several magazine articles and the last I read they did a test on an Integra, and the most they could gather was 1hp more over a high flow cat if you go without. So given that it's only 1hp difference you might as well be smog legal.

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true story:) thanks alot

dont mean to rob the thread...but how much hp gain will their be with a high flow cat?

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You don't gain much, it's more of just a principle kinda thing. If you're going to put an exhaust on your car to increase exhaust flow, then you might as well take care of every component you can. You're trying to open as much as you can. From what I remember a high flow cat only opens about .7hp, like I said before, it's not much but you wanna do it right.

Removing the cat makes more difference than 1 HP.

The last time I saw someone ran without a cat, he shot fireballs out of his muffler. If your state doesn't require smog issues i say just for for a Test Pipe.

Ok, it didn't take me long to find and I recommend everyone take a look at this good read*. What I've been trying to say, and I admit I may have not worded it very well. The difference between a de-cat test pipe and an aftermarket cat is only 1hp. You'll see good gains from either one over stock. 1 extra hp just doesn't seem worth it to me, I don't want to have to change it out everytime I want to pass emissions. If my friends can pass with their SR 240s then I'm sure it's possible, it just depends on what state you live in and if you're willing to put up with the possible headache.

*http://www.importtuner.com/tech/impp_0610_...ters/index.html

This post has been edited by GTS13: Jun 29, 2008 - 12:58 PM

And there's another consideration -- you do breathe, right?