STi exhaust mod

I understand that the stock up pipes on the US spec STi are packed with palladium catalyst. There are several manufacturers of catalyst free pipes, which claim to reduce throttle lag and midrange hp.

Question: Is it possible to unbolt the stock pipe, remove the catalyst and get the same performance gain?

Would the chip need to be reflashed?

Thanks

Philip

Reply to
Philip Procter
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Yes it can be gutted, but you MIGHT not get the same performance gain. Reason being that most aftermarket exhaust components are 3" or 3.5" and the factory is 2.5". If all you are doing is pulling the cats I would suspect the performance would be similar to aftermarket by gutting them. If you plan on full turboback exhaust, I'd look into aftermarket pieces personally. The one thing I'm not sure about is if the STi uses a 3 cat system like the WRX does. If so, you might want to look into just replacing the up-pipe & downpipe w/ a cat-less APS unit (really any up & down pipe will be fine, APS is my personal favorite for subaru parts...even though I use a Perrin up-pipe and PDE downpipe which I bought before I knew about APS), it will cost you, but it will be worth it IMHO.

No. BUT you might want an ECU reflash (EcuTec) or go w/ some sort of aftermarket engine management (UTEC, Element Tuning ECU, Vishnu, Etc...) to extract the most performance out of the vehicle. Also, you may get a check engine light if you remove/gut the cats as well. There is a CEL eliminator you can buy OR you can search

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as I believe there is a DIY mod to eliminate the CEL as well.

No problem

Chuck

Reply to
WRXtreme

The STi does not have a catted up-pipe - only the WRX does. The STi up-pipe is cat-free, so a lot of WRX guys buy them (from STi owners who upgrade their headers and uppipe), to avoid having to try to gut theirs.

Reply to
Patrick Fisher

Does the STi up pipe fit without any modifications? The up and down pipes are on my list of desired mods to my currently stock silver 04 WRX.

David

Reply to
David Edgley

Fitment is fine: "factory fit" one might say. ;) The STi up-pipe is a much better choice IMO than most aftermarket up-pipes due to the inclusion of heat shielding and a flex joint.

The only mod you'll need to do is to add a 2.2k resister in place of the WRX EGT sensor as the STi up-pipe has no EGT bung to mount it...the EGT sensor is no longer needed as it is only there to protect the (now nonexistant) cat.

Brent.

Reply to
brentlz

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