cat or no cat? pros and cons
 

almost done swapping in my engine and just wanted to know what you guys thought about using a cat. I currently have a straight pipe but I also have an extra cat just lying around. So I still dont know if I should use the cat or not

any help would be great
thanks

Re: cat or no cat? pros and cons
 

Installing a cat will reduce pollutants emitted from your exhaust.

Re: cat or no cat? pros and cons
 

If you dont live in a state where they require emissions check leave it off! Better for power

Re: cat or no cat? pros and cons
 

I live in california but i dont need smog for 2 years so im just trying to see if i can get any positive effects by running a cat
maybe keep the engine healthier something

Re: cat or no cat? pros and cons
 

Since you live in Cali run a cat. If you get stopped they could tow your car for illegal mods with no cat. On a mild motor even a stock cat will not take much power away. I say 3-5 whp less is worth not getting messed with by the 5-O.
On the other side of the argument running a test pipe will free up the exhaust can gain power, more in a modified or turbo motor. My civic passed emissions with OBD1 conversion so I can get away without running a cat, but it is still on there for now at least.

Re: cat or no cat? pros and cons
 

3-5 whp is a lot more than what you would get. It's more like 1 whp. It's not worth it man. Just put it on. It will also make your car quieter and less raspy.

Re: cat or no cat? pros and cons
 

Cats really arent one of those things that make or break your ride on the line. The HP gain from removing it is a drop of water in a lake. Nothing big, but still a HP gain. On the other hand, if you can withstand the little voice saying "get every HP outta this 4 banger!" then i would leave it on simply to keep your ride from being one of those annoying teen cars that make everyones teeth grind when they whip by all rattly (is that even a word?)

Re: cat or no cat? pros and cons
 

False!

Listen to this man, he is exactly correct!

Re: cat or no cat? pros and cons
 

Seen it time and time again do a pull on the dyno, put on a test pipe do another pull and a good 3whp on a stock setup, seen up to 10 on a LS Vtec and over 30whp on a turbo GSR at already had a high flow cat on it. As power levels increase as with turbo application the need for low exhaust back pressure plays a key roll in overall out put and performance. As I said I say this but in realy world DD practice I have a OEM 99 Si cat on my 98 Civic with LS Vtec. Once I get my turbo kit together the cat goes bye bye.

Re: cat or no cat? pros and cons
 

just something i found to clear things up...


http://www.importtuner.com/tech/impp...ct_or_fiction/

Re: cat or no cat? pros and cons
 

Nice, exactly whay i was saying!

As far as people who see a difference on a dyno, there could be a couple reasosn for this.....

- the original cat could be plugged up, so adding anything free flow would add power

- sometimes to dyno a car from literally one run to another can vary, due to thing like temp of the engine, temp of the air, density...any number of things

Re: cat or no cat? pros and cons
 

more fumes if you dont use a cat also.

Re: cat or no cat? pros and cons
 

Look up test pipe on eBay that's your friend!!! Easy swap for future smog test as well!!!

Re: cat or no cat? pros and cons
 

He already has a test pipe......

Re: cat or no cat? pros and cons
 

I guess no one gives a shit about the environment anymore...

Re: cat or no cat? pros and cons
 

if you like rolling around in federally illegal car all day for MAYBE 1whp then be my guest. especially in cali. you might not have to get it smogged soon but like someone said if you get pulled over and they wanna look bye bye car. id imagine a nice fine would come with it too.

so in the end? put it on. at worst buy a hi flow cat. i have one on my NA build and i'll have one on my turbo. i like having a planet and no raspy bees.

http://autos.yahoo.com/maintain/repa...ques081_0.html

Re: cat or no cat? pros and cons
 

The day will eventually come when all states have emission testing and CA is usually the model for these programs. This will probably come about as the result of federal highway funding carrot and stick.

I'm in a state that did away with emissions testing when the government turned 51% red.

It's only one election away at any time.

Enjoy it while you can. :cry:

Re: cat or no cat? pros and cons
 

Exactly, I've seen more cars have issues due to clogged cats and that's why I choose to not run them. Yes you can gain maybe 1whp in a car with a fairly new cat but in most of these civics were talking cars with 100k miles or more.... these cats aren't as efficient any more. There is more to gain than 1whp and a better peace of mind.

BUT since the OP lives in the no fun state of Cali, put it on when emissions time comes around lol

Re: cat or no cat? pros and cons
 

Whenever I've run no cat, my civic would be louder overall but especially loud for a certain RPM range from 2500 to about 3100. Very annoying. No noticeable difference in power when running a cat, huge difference in noise.
Also, when a car with no cat is left idling, the fumes are pretty serious and people nearby may complain. Happened to me a few times.

I've seen the biggest difference on dyno numbers with turbo and other high horsepower cars. That's where having a bolt-in decat for racing would be important. On the street with the average Honda, I would recommend running a cat.

Re: cat or no cat? pros and cons
 

Over the years I have read several tuner magazine articles that have argued both sides of the cat debate. When it comes down to it I believe what the dyno tells me not the he said she said my firend on 15whp from a gutted cat BS.

Re: cat or no cat? pros and cons
 

Your car must run pretty rich.
This is what I was saying. Big gains with a test pipe can be had in a high power NA or turbo motor but gains are minimal on a mainly stock motor, but I have seen small gains on mild motors as well.

Re: cat or no cat? pros and cons
 

Cat helps out ur muffler, no cat equals misfires...sometimes

Re: cat or no cat? pros and cons
 

okay so i just finished my swap today and since i have the itr headers with the 2.5 tip
both my cat and my test pipe dont fit

so now that I have to get either a test pipe or a cat
which do you recomment?
Ive heard good reviews on magnaflow catalictic converters but the direct bolt on itr one that is state legal in california cost 300-500 dollars and im not really trying to spend that much

not too familiar with muffler shops so idk how much they charge for custom test pipes or welding

so what do you guys think are better choices?

Re: cat or no cat? pros and cons
 

Either way, you're going to be spending an assload of cash for a cat. Price out the magnaflow direct fit, plus the piping you'll need on the other side, then call a couple shops and see how much they'll charge to weld in a generic. Either way, don't buy your cat from the shop - shop prices are never cheap.

Re: cat or no cat? pros and cons
 

Thank you.

This thread is so full of misinformation and poorly articulated points that are wrong.

Bottom line:

___________________

Removing your catalytic converter increases the harmful emissions from the car.
Removing the catalytic converter increases the noise/raspiness of the exhaust note.
Removing your catalytic converter is not a worthwhile power upgrade. Often times a catalytic converter can optimize flow velocity and result in better low end power while sacrificing a minimal flow rate at the top of the RPM band.

Dynos have again and again proven that a catalytic converter is not this obstructive power killer of car performance. Get a 300 cell high flow catalytic converter, and make power where it makes sense to and leave your exhaust alone.

Save the environment, save our ears, save your image.

Run a catalytic converter unless you're running open header at a drag strip.