Newbie here, questions on up and down pipes
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Newbie here, questions on up and down pipes
Im a newbie here , i have a 2002 WRX sedan, currently running a injen intake, AEM pully and greddy cat back exhaust. Next i would like to add a up and down pipe, possibly a header. I want the gains but not neccesarly the noise, could anyone recomend some up and down pipes with highflow cats, so i dont have to remove any cats. Or any other mods that would be good for my car.
Any assistance would help,
IMPRZME
Any assistance would help,
IMPRZME
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From: Reno, NV
Car Info: 1993/2000/2001 GF4 mostly red
This thread belongs in this forum. That's probably why you didn't get a response. I would try looking at www.gruppe-s.com for some options, several people on here have the pipes available there.
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there are both up and down pipes with cats in them, although i can think of the names off the top of my head. I however, dont reccomend putting a cat in the up pipe, because it robs so much power. Same with the downpipe for that matter, but it sounds like you want cats. i would go with a catted downpipe, and i high flow cat in the center section, and i think you should be alright. Noise is not a problem if you keep the stock axelback, however it robs some power. I know TurboXS makes a pretty quiet system. BUt you would need to find out who advertises a low sound. Hope this helped
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Joined: Nov 2002
Posts: 18,369
From: Reno, NV
Car Info: 1993/2000/2001 GF4 mostly red
There are 2 major reasons that Subaru put the first cat in the uppipe. Biggest one is reaching light-off temp- the turbo is a big fat heat sink, so it takes a lot longer for enough heat energy from the exhaust to transfer to it so that it will react the emissions. Putting one in front makes this hapen faster.
Second, almost all cars now have multiple cats because they each use different coatings to create different chemical reactions, which produce fewer emissions once everything leaves the tailpipe. Because of that, removing the one in the uppipe makes the others much less effective.
There is a simple solution however. If you get a downpipe with a good, high-flow 3-way catalytic converter, you'll lose very little efficiency in reducing emissions, except at cold startup. This is going to be the easiest route to take. It's not too hard to find downpipes with those in them. This way you can still pass a sniffer test if you can find someone to wink at your visual.
Best part is, cats like Random Tech's and Cobb's flow very close to as well as a straight pipe. Plenty of available horsepower via this setup.
Second, almost all cars now have multiple cats because they each use different coatings to create different chemical reactions, which produce fewer emissions once everything leaves the tailpipe. Because of that, removing the one in the uppipe makes the others much less effective.
There is a simple solution however. If you get a downpipe with a good, high-flow 3-way catalytic converter, you'll lose very little efficiency in reducing emissions, except at cold startup. This is going to be the easiest route to take. It's not too hard to find downpipes with those in them. This way you can still pass a sniffer test if you can find someone to wink at your visual.
Best part is, cats like Random Tech's and Cobb's flow very close to as well as a straight pipe. Plenty of available horsepower via this setup.
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