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Old 08-31-2005, 05:35 PM   #1
mannslayer
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Question Removing Cats and Straightpiping?

Hey guys I am from Canada where there is no type of vehicle or emissions inspection. I am considering removing the 3 cats from my 02 2.5RS and doing a straight pipe to my new Megan Racing muffler. However I noticed the oxygen sensor is located after the cats instead of before. I don't know too much about exhuasts or cars in general and the goal is to get the angriest grumble possible without dumping a lot of money.

Does anyone know if this is alright to do without causing any major problems?
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Old 08-31-2005, 05:57 PM   #2
DrBoy01
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Quote:
Originally Posted by mannslayer
Hey guys I am from Canada where there is no type of vehicle or emissions inspection. I am considering removing the 3 cats from my 02 2.5RS and doing a straight pipe to my new Megan Racing muffler. However I noticed the oxygen sensor is located after the cats instead of before. I don't know too much about exhuasts or cars in general and the goal is to get the angriest grumble possible without dumping a lot of money.

Does anyone know if this is alright to do without causing any major problems?
IIRC, there should only be two cats in the cat section of your exhaust system. If you replace that with a catless "test" pipe, I would recommend having O2 sensor bungs put in the stock locations. You might get a CEL, but there are several ways to fix that.

Your car will also be really, really loud. I have Borla headers, a 2.0" catless track pipe, and a Stromung catback with a custom 12" resonator in the midpipe. It's not unbearably loud, but loud enough to make the car very conspicuous wherever I go.
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Old 08-31-2005, 06:46 PM   #3
mannslayer
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What exactly is a CEL and what are the ways of fixing this?
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Old 08-31-2005, 06:47 PM   #4
svek
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check engine light bhrody


there is a cel fix sold at www.boxer4racing.com just for doing the above. it works for some people and doesnt for others.
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Old 08-31-2005, 08:12 PM   #5
impr25rs
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I am not sure on the 02-03 cars, but the 98-01 car have the rear O2 sensor located far back on the cat section. On my 04 the rear O2 sensor is literally right behind the first cat, with the front O2 sensor in the front of the first cat. So you may have to extend the O2 sensor wire like I will if you buy a premade "track" pipe. Or if you have one made for you, make sure you get them in the right place.

Secondly I would HIGHLY recommend getting a fairly good size resonator put in your midpipe. It will make it more bearable and keep Mr. Popo from givin' ya crap. You can use CEL fixes, but they probably won't work. The mechanical CEL fixes will probably just make your O2 sensor last a little longer.
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Old 08-31-2005, 09:50 PM   #6
hendo2.5
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Quote:
Originally Posted by mannslayer
Hey guys I am from Canada where there is no type of vehicle or emissions inspection. I am considering removing the 3 cats from my 02 2.5RS and doing a straight pipe to my new Megan Racing muffler. However I noticed the oxygen sensor is located after the cats instead of before. I don't know too much about exhuasts or cars in general and the goal is to get the angriest grumble possible without dumping a lot of money.

Does anyone know if this is alright to do without causing any major problems?
dude, the canada that i'm in makes you get an emissions test every 3 years and whenever the car changes owners. you get in huge tihs if you get pulled over (which you will with what you're proposing), and fined up the poopshoot for no cats.
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Old 08-31-2005, 10:51 PM   #7
mannslayer
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Yes there's AirCare in Vancouver, and probably other areas in the country, but nothing of that sort where I am from. It's perfectly legal to remove the catalytic converters here, but I'll probably be over the legal decibel limit. I do however, have a removable silencer I can put in and out.
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Old 08-31-2005, 10:54 PM   #8
Defiantguy
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It's not that loud if you have a resonator in your exhaust somewhere. CELs can be a bitch though.
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Old 09-01-2005, 07:43 AM   #9
hendo2.5
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Quote:
Originally Posted by mannslayer
Yes there's AirCare in Vancouver, and probably other areas in the country, but nothing of that sort where I am from. It's perfectly legal to remove the catalytic converters here, but I'll probably be over the legal decibel limit. I do however, have a removable silencer I can put in and out.
where are you?
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Old 09-01-2005, 11:04 AM   #10
mranlet
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Unless you go with standalone engine management, you will need a good signal on your O2 sensor to avoid going into open-loop EFI. In other words, if your O2 sensor is removed or stuck right in a hot flow, you will be toggling between super rich and super lean, which can cause you problems down the line.

The Boxer4Racing O2 extraction bung (also available through subysolutions) just pulls the O2 sensor out of the flow of the gas and gives you a proper signal. IIRC, you have one sensor before the cat and one after - the forward one will be the one critical to your A/F control, while I think the aft one is just an emissions control/redundancy measure. Either way, you ought to try and reposition them as accurately as possible so as not to mess with your EFI.

I had straight pipe side exit exhaust and dual open wastegate, and it was loud as ****. My only saving grace was that it was a '90 Legacy Wagon, so cops just figured that the muffler fell off (until I shot flames out the side). However, for a daily driven car that is a little more conspicuous, you will probably want some sort of resonator to maintain a little bit of backpressure (no turbo) and keep the pingy-ness down a little. At least in the US, the police get more worked up about nasal pingy-sounding exhaust than low rumbly exhausts. Where I live in FL, It's pretty rare that you see a muscle car or Subaru or V-twin pulled over for exhaust, but Hondas and modified sport bikes are exhausted all the time.
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Old 09-01-2005, 05:13 PM   #11
t3hWIT
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Quote:
Originally Posted by mannslayer
I do however, have a removable silencer I can put in and out.
no way man.

my situation:

1997 Impreza, 2.2L, 2 cats. 2 1/4 catback. it was still pretty damn loud with the silencer in. with it out....

it will be installed on a 95 1.8L with one cat in a couple weeks. if this thread is still open, ill let u know how it was loud-wise.

my point here is that the removable silencer isnt gonna quiet it down THAT much. id reccommend a glasspack (or even two) further up the line in the size of your "test pipe" that way it quiets it down to a almost legal level, with minimal loss of flow.
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