I have a spare used cat and a Nissan master technician told me to gut it out and re-install it and I will get a hp gain. I have never done this and was wondering if this is really going to help and if it does what are the pro's/con's of doing this?

you probably wouldn't notice much of a difference besides ur exhaust would be louder. Your exhaust would smell bad too. Plus u would be poluting and might not pass emissions if u have them there.

Gut your cat. It will not smell. I have also heard that with a cat on your car and you run certain types of fuel it can plug your cat. Besides, didn't the E.P.A. come out with some test results that since there have been catalytic converters on automobiles, starting in the 70's, that the exhaust is putting some new harmful gas into the atmosphere? All I know is that I have a Hotshot header with 2 1/4 exhaust with no cat and it flows. Of course we don't have emissions test here either. My 2 cents...

From what I have heard the cat on SR20 cars is comparatively large, especially for a four cylinder. No one has really reported a gain from gutting it or replacing it with a test pipe. I would leave it on; it's legal and environmentally sound.

Hey, I'll trade you cats plus cash! =)

I gutted mine after I melted down the core and want to swap it for one in working condition.

Unless you're running a really big turbo, you're not really going to get much gain from gutting the cat. And really, you shouldn't gut the cat as it could cause more turblent flow which could actually lose power. If you must, stick a test pipe in there. The stock cat is 2.5" inner diamtere if I remember correctly which is pretty friggn big which is why no one really sees a gain buy doing anything to it.

And being that I like breathing clean air, cats reduce emissions by 95%+; just something to think about.

Khiem

I asked Alex the same question yesterday and his friend ran his car at the track with and without the cat and his car ran .7 seconds faster with cat. Cant explain it but im puttin my cat back on because when I downshift it makes a horrible fart noise because there is more gas trying to come out than my stock piping diameter can handle. I guess it would vary because I still have the ga16de in mine.

A cat does not have to be a flow restriction. If the cat is in working order keep it. If you gut it you will lose power of a properly working cat in the same car that is not turbo. If you run a turbo do us all a favor an put a 3 inch cat on. Air quaility should matter to everyone. Many cars with cats produce great power. IF you fail to monitor our own behavior the sooner the MAN will wise up and do it for you.

Steve

My SE-R is primarily only used for racing. I have a test pipe that I have not installed, mainly because i'm scared of the rusted bolts and the fun always associated with that, so I'm holding off on putting it on. I have no exp. with cats on nissans, but a friend and I autocrossed an '86 Jetta GLI 8v (adv timing) so we always ran no less than 96 octane, the cat started to clog, we gutted the cat with a coat hanger, reinstalled it, and the thing ran way faster than it did before. But the added noise and pollution isn't worth it on a daily driver.

Removing Your CAT:

IMHO -

It's not that noisy.
It makes your throttle slightly more responsive.
It "feels" better at higher engine speeds.
It's necessary to get more power for turbo applications (this isn't an opinion, it's a well-documented fact).
It helps a bit for those squeezing nitrous.

It does stink sometimes.
You get a bit of black gunk on your exhaust tip but not on your bumper or anything like those cars that are burning oil.
Environmentalist wackos give you a hard time when they find out about it (or smell it).

Originally posted by Jason92Classic
Removing Your CAT:

IMHO -
...Environmentalist wackos give you a hard time when they find out about it (or smell it).

Funny. You like to breathe?

Chris