Engine/Power - EJ20T (pre-2006 WRX and JDM) There is replacement for displacement, it is forced induction - OEM 2.0 liter turbo engines in the USDM WRX. 90-94 Legacy Turbo EJ22 turbo engines can also be discussed here.

Downpipe Cat Pro/Con

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Old Jan 7, 2006 | 02:48 PM
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wvinfernovw's Avatar
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Question Downpipe Cat Pro/Con

Is there a difference in reference of PowerGain and Smog/Emissions test to where the CAT is located on the DP?...

-i heard that the cat is more effectived when its located on the upper portion of the DP instend of being on the bottom half like the Turbosx DP.

-so far im passing the emissions test with a invidia Uppipe w/ stock full turboback. After gettin a aftermarket turboback w/ CAT, will or can i still pass the emissions?

Thanks
Old Jan 7, 2006 | 08:18 PM
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you will not pass the visual but you might pass the emissions. So you may pass and you may not. You will not notice the differnce in catless or catted(on a stock turbo). And yes it does work better when its located closer to the turbo because it gets heated up faster. I think i answerd most of it for you. Just get a catted downpipe and call it a day
Old Jan 7, 2006 | 10:28 PM
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Talking

haha yea probably will... thank alot
Old Jan 17, 2006 | 11:56 AM
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Why would this not pass visual? Is the cat on an aftermarket downpipe that far up where its hidden?
Old Jan 17, 2006 | 07:18 PM
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dnot worry about getting a catted downpipe. get a catless downpipe... still pass visual and probably pass emissions, gain more horsepower, and not worry about where the cat is located! haha
Old Jan 18, 2006 | 08:16 AM
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Originally Posted by projectwrx
dnot worry about getting a catted downpipe. get a catless downpipe... still pass visual and probably pass emissions, gain more horsepower, and not worry about where the cat is located! haha
Is 5whp really worth not passing an emissions test? Here in Kalifornia, a cop could send you to the smog ref after a roadside visual inspection. Despite what some believe, cops are smart enough to tell if there are zero cats on your car.

To answer the original poster's question, the cat will work more efficiently when closer to the heat source (i.e.: turbo). However, we really haven't seen a lot of results from smog tests with cats in different positions, so a cat farther down the line may work just fine. Vishnu did do some smog testing on one of their Stage 2 cars (VF30, injectors, hiflow catted downpipe, catless uppipe, fuel pump) and it passed the sniffer test.

In reality, if you are really concerned about passing the test (as many of us in Kalifornia are), swap the stock parts back in for the test. You can swap a full TBE in an hour.
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