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Old 11-06-2006, 11:18 PM   #1
nineleft
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Default Cobb high flow vs. cattless

Is there any visual difference between the high flow dp and cattless dp. as far as visual inspections for emissions testing. Thanks
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Old 11-06-2006, 11:19 PM   #2
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yes, there is a clear differnce. The Cat is in the larger rounded section of the downpipe, you cant miss it
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Old 11-06-2006, 11:20 PM   #3
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Yes, the high flow cat dp will have a bulge for the cat, whereas the catless dp will be the same diameter throughout.

Edit: Alex beat me!
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Old 11-06-2006, 11:44 PM   #4
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Originally Posted by amukaoen View Post
yes, there is a clear differnce. The Cat is in the larger rounded section of the downpipe, you cant miss it


Thanks, so I guess if a visual inspection is made and it's cattless, no bulge no pass
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Old 11-07-2006, 11:18 AM   #5
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Not quite if it looks like it has been changed no pass, most states have laws that no changes to the emesions system be made ( yes adding 25 cats would be the same). If you have a new SS downpipe that they see has been changed they may not pass you. Running with a cat will only help if they only do the sniff test, otherwise throw the stocker back on for the test. Just My .02.
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Old 11-07-2006, 11:22 AM   #6
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From what I understand IL doesn't do visual, just odb2 and gas cap. You should be fine either way as long as you don't have CEL's. Do us all a favor though and get a catted DP. It only costs a few hp at most and helps reduce the smog.
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Old 11-07-2006, 11:25 AM   #7
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+1 on the catted DP. It really is worth the marginal loss in HP to keep things a little cleaner.
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Old 11-08-2006, 12:48 AM   #8
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dont quote me on this, but i heard some krazy fact that every catless car pollutes the same as 20,000 catted cars do. !!!

Its worth the 4-5 hp.. which is what like.. 1-2 whp? Not a bad tradeoff if I can keep the air a little cleaner for our future generation.
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Old 11-08-2006, 03:52 AM   #9
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The cat figure is crap. I had an 89 mustang 5.0 (stroked to a 331) that was tuned VERY well by a local tuner. The car ran great if a bit lean. I put it on an emissions tester and it actually produced LESS pollutants than the testing owner's brand new Honda Accord. It is about how complete the combustion process is, not how many pollution control devices that you shove on the car. Mine failed the visual portion only and I had to throw a stock h pipe on there to pass. The owner was amazed and said that he would love to pass me, but said that he was unable due to the visual potrion and he did not want to lose his livelyhood. I completely understood this and came back another day with cats (car ran worse with cats but passed as it was not tuned for the 4 cats that the mustang stock h pipe has).

The end result is from the factory cars need these devices to keep things clean. The reason behind this is that the tune from the factory is very generic to enable cars to run well in a wide variety of climates, altitudes and conditions. Because of this the same car has to run a safe amount of fuel, a safe set of parameters, etc. To achieve these levels they have to run kinda rich (kinda like the ots Cobb maps). Cats help deal with the excess. How do they do this? They actually send a signal to the computer telling it to run leaner and have more o2 in the exhaust to help the process. Yes they work well, but I guarantee that a well tuned car will put out less emissions than the standard land yacht SUV that you see driving around. Sure when you are in full boost with 10.0:1 AF ratios you are gonna dump some fuel, but realistically most people don't stay in the boost all the time on their street driven cars.

Ever driven behind a car with high flow cats? Maybe a vette or viper that has high flow cats from the factory? When they step on it you still see some dark smoke come out. The cats only do so much and when you jam on the throttle you still get the majority of the pollution out the pipe. Want to save the environment and hug some trees? Go electic or better yet, run a car on E85 or hydrogen. Want to drive a mild street rod like the WRX uncapp the exhaust. I was able to gain a spool sooner and save my turbo from an untimely death with an up-pipe that Subaru is now putting on all their Wrx's.

You can still pass with a high flow 3rd cat in most places. I have not encountered too many emmissions stations that look too hard...they see a cat (gutted, high flow or stock) and they pass ya.
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Old 11-08-2006, 04:00 AM   #10
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Here is another interesting link:http://www.junkscience.com/news2/catalyt.htm

Apparently these catalytic converters that you guys all praise so highly on this site as being the end all be all tree hugging helper are actually causing 300x more pollution in the form of nitrous oxide than if the car did not have them.
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Old 11-08-2006, 11:13 AM   #11
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Originally Posted by crashtke View Post
car ran worse with cats but passed as it was not tuned for the 4 cats that the mustang stock h pipe has

So how do you think it would have run if your car HAD been tuned for the cats? Or if it had high flows with a good tune? The small gain in power is not worth the pollution. How many catless cars out there actually have this "perfect" tune you talk about? A friend of mine was running an aftermarket DP with TWO cats. He dynoed exactly 1 HP less with the catted DP (324 WHP IIRC).
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Old 11-08-2006, 11:53 AM   #12
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Did you folow the link and see what the EPA found out about your cats? It's a good read! Cats are bad!
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Old 11-08-2006, 01:09 PM   #13
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Did you folow the link and see what the EPA found out about your cats? It's a good read! Cats are bad!
Yeah I did, didn't sound like a very scientific article to me (and didn't have any info on the "studies" they keep quoteing) so I did some research of my own. Sounds like junkscience.com is just that, junk science, paid for by corporations and right wing political interests:

http://www.mapcruzin.com/greenwash/
http://timlambert.org/2004/02/milloy/
http://www.google.com/Top/Society/Is.../Junk_Science/

Come up with an article by a well respected main stream source and I will believe it.
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Old 11-09-2006, 01:10 PM   #14
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Yeah I did, didn't sound like a very scientific article to me (and didn't have any info on the "studies" they keep quoteing) so I did some research of my own. Sounds like junkscience.com is just that, junk science, paid for by corporations and right wing political interests:
Listen, I know the socialists won on Tuesday, but lets not get overexcited here. Global warming/environmental worshippers put out more (and deemed more by acadmia/politicians/media) garbage science to promote their ideal than those that poke holes in the theory. Remember, in the 70's "they" were warning us all of the "pending ice age".

Not to go out on a limb and start labelling things politically or anything.......
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Old 11-09-2006, 01:46 PM   #15
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Originally Posted by spoonracing13 View Post
Listen, I know the socialists won on Tuesday, but lets not get overexcited here. Global warming/environmental worshippers put out more (and deemed more by acadmia/politicians/media) garbage science to promote their ideal than those that poke holes in the theory. Remember, in the 70's "they" were warning us all of the "pending ice age".

Not to go out on a limb and start labelling things politically or anything.......
Just because you don't want to believe something doesn't make it false. The links that I posted give a background on the person who maintains the junkscience site. The site is a corporate funded site run by a guy who has some pretty serious connections to the tobacco industry among others. Not exactly the type of person who I would trust to get science info from. I wasn't saying that people should look to the "socialists" as you call them for science guidance. I was saying that before you jump to conclusions and believe anything you see online to find out what the sources are and where they are getting their information. The fact that the guy who runs the site has the background and funding that he does makes me highly skeptical of what he says. In addition the article itself continuously makes references to things but never quotes a source or a link to the studies that it mentions.

Like I said in my previous post, show me an unbiased (or as close as possible) article from a reputable source that says this and I will believe it. Based on the funding and background of the guy maintaining the site, junkscience.com is neither of these things.
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Old 11-09-2006, 02:01 PM   #16
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Cat's = good unless they have fur, those are evil
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Old 11-09-2006, 02:11 PM   #17
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Originally Posted by crashtke View Post
Did you folow the link and see what the EPA found out about your cats? It's a good read! Cats are bad!
You trust the EPA?
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Old 11-09-2006, 02:15 PM   #18
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Quote:
Originally Posted by crashtke View Post
The cat figure is crap. I had an 89 mustang 5.0 (stroked to a 331) that was tuned VERY well by a local tuner. The car ran great if a bit lean. I put it on an emissions tester and it actually produced LESS pollutants than the testing owner's brand new Honda Accord. It is about how complete the combustion process is, not how many pollution control devices that you shove on the car. Mine failed the visual portion only and I had to throw a stock h pipe on there to pass. The owner was amazed and said that he would love to pass me, but said that he was unable due to the visual potrion and he did not want to lose his livelyhood. I completely understood this and came back another day with cats (car ran worse with cats but passed as it was not tuned for the 4 cats that the mustang stock h pipe has).

The end result is from the factory cars need these devices to keep things clean. The reason behind this is that the tune from the factory is very generic to enable cars to run well in a wide variety of climates, altitudes and conditions. Because of this the same car has to run a safe amount of fuel, a safe set of parameters, etc. To achieve these levels they have to run kinda rich (kinda like the ots Cobb maps). Cats help deal with the excess. How do they do this? They actually send a signal to the computer telling it to run leaner and have more o2 in the exhaust to help the process. Yes they work well, but I guarantee that a well tuned car will put out less emissions than the standard land yacht SUV that you see driving around. Sure when you are in full boost with 10.0:1 AF ratios you are gonna dump some fuel, but realistically most people don't stay in the boost all the time on their street driven cars.

Ever driven behind a car with high flow cats? Maybe a vette or viper that has high flow cats from the factory? When they step on it you still see some dark smoke come out. The cats only do so much and when you jam on the throttle you still get the majority of the pollution out the pipe. Want to save the environment and hug some trees? Go electic or better yet, run a car on E85 or hydrogen. Want to drive a mild street rod like the WRX uncapp the exhaust. I was able to gain a spool sooner and save my turbo from an untimely death with an up-pipe that Subaru is now putting on all their Wrx's.

You can still pass with a high flow 3rd cat in most places. I have not encountered too many emmissions stations that look too hard...they see a cat (gutted, high flow or stock) and they pass ya.

In order to reduce emissions, modern car engines carefully control the amount of fuel they burn. They try to keep the air-to-fuel ratio very close to the stoichiometric point, which is the calculated ideal ratio of air to fuel. Theoretically, at this ratio, all of the fuel will be burned using all of the oxygen in the air. For gasoline, the stoichiometric ratio is about 14.7:1, meaning that for each pound of gasoline, 14.7 pounds of air will be burned. The fuel mixture actually varies from the ideal ratio quite a bit during driving. Sometimes the mixture can be lean (an air-to-fuel ratio higher than 14.7), and other times the mixture can be rich (an air-to-fuel ratio lower than 14.7).
The main emissions of a car engine are:

Nitrogen gas (N2) - Air is 78-percent nitrogen gas, and most of this passes right through the car engine.
Carbon dioxide (CO2) - This is one product of combustion. The carbon in the fuel bonds with the oxygen in the air.
Water vapor (H2O) - This is another product of combustion. The hydrogen in the fuel bonds with the oxygen in the air.
These emissions are mostly benign (although carbon dioxide emissions are believed to contribute to global warming). But because the combustion process is never perfect, some smaller amounts of more harmful emissions are also produced in car engines:
Carbon monoxide (CO) - a poisonous gas that is colorless and odorless
Hydrocarbons or volatile organic compounds (VOCs) - produced mostly from unburned fuel that evaporates
Sunlight breaks these down to form oxidants, which react with oxides of nitrogen to cause ground level ozone (O3), a major component of smog.


Nitrogen oxides (NO and NO2, together called NOx) - contributes to smog and acid rain, and also causes irritation to human mucus membranes
These are the three main regulated emissions, and also the ones that catalytic converters are designed to reduce.

http://auto.howstuffworks.com/catalytic-converter1.htm
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Old 11-09-2006, 02:40 PM   #19
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Cat's = good unless they have fur, those are evil

Agreed!

My son loves dogs and every other animal he has seen so far (he is 16 months old) with one exception. My parents are babysitting my brothers cats until they find a house and last time we went to visit he was scared to death of them. He saw one of them and ran away crying. He had never seen a cat before in his life.
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Old 11-09-2006, 02:48 PM   #20
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In order to reduce emissions, modern car engines carefully control the amount of fuel they burn. They try to keep the air-to-fuel ratio very close to the stoichiometric point, which is the calculated ideal ratio of air to fuel. Theoretically, at this ratio, all of the fuel will be burned using all of the oxygen in the air. For gasoline, the stoichiometric ratio is about 14.7:1, meaning that for each pound of gasoline, 14.7 pounds of air will be burned. The fuel mixture actually varies from the ideal ratio quite a bit during driving. Sometimes the mixture can be lean (an air-to-fuel ratio higher than 14.7), and other times the mixture can be rich (an air-to-fuel ratio lower than 14.7).
Isn't it 14.7 moles air to 1 mole fuel? Pounds are the wrong measurement.
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Old 11-09-2006, 04:23 PM   #21
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Wow I we are still on the topic but barely...

If you have the money, go with the catted version. It will get you past sniffer test, and of course it doesnt smell as bad as a catless exhaust.

I know imediately when I'm behind a catless WRX. That means a cop will too, and he can pull you over for suspected illegal exhaust esp. on a WRX he can just say its too loud. Although people say it cost 5 hp I really doubt it does. Every dyno run of the same car is slightly different....I bet if you were to average catted vs non catted it would be more like 2 hp over 10 runs....

If you dont have the cash and you want every possible HP then go catless. Its highly illegal and about 50% of the people on this forum are using it without incident...

Good luck....
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Old 11-09-2006, 06:37 PM   #22
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Wow I we are still on the topic but barely...

If you have the money, go with the catted version. It will get you past sniffer test, and of course it doesnt smell as bad as a catless exhaust.

I know imediately when I'm behind a catless WRX. That means a cop will too, and he can pull you over for suspected illegal exhaust esp. on a WRX he can just say its too loud. Although people say it cost 5 hp I really doubt it does. Every dyno run of the same car is slightly different....I bet if you were to average catted vs non catted it would be more like 2 hp over 10 runs....

If you dont have the cash and you want every possible HP then go catless. Its highly illegal and about 50% of the people on this forum are using it without incident...

Good luck....
Speaking of loud. How much louder is the Cobb cat back vs. stock cat back. ei full TB vs. down pipe only?
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Old 11-09-2006, 06:44 PM   #23
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Oh one more thing to add, if you're caught with a tampered exhuast and had intentionally removed the cat's- that's a $10,000 fine. Just thought I'd tag that on.
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Old 11-09-2006, 06:47 PM   #24
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^^^
I've yet to hear of anyone getting that pulled on them. Even in CA.
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Old 11-09-2006, 06:51 PM   #25
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Speaking of loud. How much louder is the Cobb cat back vs. stock cat back. ei full TB vs. down pipe only?
here you go buddy....

http://youtube.com/watch?v=G6tM-d6SdHI

its not too loud...but sometimes really late at night I get a little nervous driving between sky scrapers in the city because the exhaust echos so loudly...

btw thats not my car....
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