Tomorrow I'm going to get some custom exhaust pipe made for my celica. I was wondering how much louder it would be without cat. I am gonna have 2 1/4 in piping with no resonators and a muffler. Also, I heard that if you dont have a cat there will be a very noticable smell indicating you dont have one. Third, would it give me any hp gains since the midpipe would now be 2 1/4 Last, how easy would it be for a cop to tell that you dont have one. I live in alabama and we dont have to go through any emissions or vehicle inspections

NO WE DON'T welcome to the board!

If you remove your cat it will sell like a rotten egg inside and out of your car.

Either way it really won't do a whole lot power wise, in other words, the only place you will feal a difference is in your mind.

On an old corvette, gutting the cat will make twenty hp. On a celica... one or two.

Jon

I'd keep your cat on...you probably need it for backpressure reasons so that you don't lose torque. Also, your car will be very loud without a cat, and once you get pulled over for excessive noise, all a cop has to do is look under your car to see if you have a cat or not. >>

Instead of removing the cat, get a header.
It eliminates the cat.
then get a high flow cat and have it welded in somewhere in the piping.

I had a header to 2.5" piping to a muffler and it was LOUD and nasty.
I just put a glasspack in and its a quieter car now.

i got my cat removed as soon as i got my car cuz i thought it was going to make it loud but it didnt. but there has never been the smell that you guys are talking about?
DREW

-SpedToe169+Jan 8, 2004 - 6:44 AM

thanks for the advice

I'll be keeping my cat

-SpedToe169+Jan 8, 2004 - 7:44 AM

that rotten egg smell is the cat smell.... the cat has a chemical (some kinda of yellow stuff) sulfur.... all new cats smell like that... thats what i read in some mechanic article...

not sure if thats correct....but it is the sulfur

-wind+Jan 8, 2004 - 1:34 PM

I just got my exhaust completed a ffew hours ago and im impressed. I paid 60 for the pipe (2 1/4") from the cat back I had them take off the secondary cat. Then i paid 100 for a nayos muffler. It sounds really good. nice and deep but not incrediby loud. I aso got a nice power gain through the whole power band and the top end kicks ass now. Its a good bit faster through the high rpms.

The purpose of a cat is to take away all the environmentally hazardous materials that come out of your engine. The gas passes through the waves or combs of the cat and mixes with chemicals that are fixed to the cat. The resulting chemical reaction turns the hazardous gases into safe gases. For example carbon DIoxide is safe...carbon MONoxide is hazardous...a simple chemical reaction can change one to the other.

i dont know for sure the gases that come out of an engine...so dont qoute me on the cabon monoxide thing...it was just for example purposes only

This post has been edited by Doge: Jan 10, 2004 - 2:19 AM