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2010 XT Limited 4EAT
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Discussion Starter #1
How many of the pipes on the SH contain CATS? How many of these can be removed without having an affect on passing emissions testing or causing odor?
 

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2010 Forester Auto
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368 Posts
In PA if you remove any of them your gonna have a CEL kick on and fail a visual look. there are two cats I believe on the XT version, I have an NA and I know I have two cats, the XT may be different.
 

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2009 2.5xt 6 Speed Swap version 8 6 speed sti trans with r180
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4,150 Posts
Seems like theres an upper and lower Cat on our models. Depends on how they do your emissions test. Many places will only check for a CEL light and not check the actual emissions on a newer vehicle. You can always put a higher flowing catylitic converter in place. The Catted CNT downpipe is the cheapest i know of. Something in the mid 300 dollar range for the whole pipe. You'll want a tune after switching though.

Edit: Only 1 pipe contains both cats. There is no cat on the uppipe like the older models. The downpipe coming out of the turbo is the only pipe. The mid pipe contains a resonator thats kinda boxy and flat but it's not a cat.
 

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Discussion Starter #4
Seems like theres an upper and lower Cat on our models. Depends on how they do your emissions test. Many places will only check for a CEL light and not check the actual emissions on a newer vehicle. You can always put a higher flowing catylitic converter in place. The Catted CNT downpipe is the cheapest i know of. Something in the mid 300 dollar range for the whole pipe. You'll want a tune after switching though.

Edit: Only 1 pipe contains both cats. There is no cat on the uppipe like the older models. The downpipe coming out of the turbo is the only pipe. The mid pipe contains a resonator thats kinda boxy and flat but it's not a cat.
Thanks a lot for this, just to clarify for myself - So the only pipe on the SH that contains a cat is the downpipe? So basically, if I replace the downpipe make sure to get a cat'ed one?
 

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2009 2.5xt 6 Speed Swap version 8 6 speed sti trans with r180
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Yes. My suggestion is the Catted CNT and a Cobb Accessport with stage II applied. The power is fun, the cat flows freer and you should still pass emissions either way they do it.
 

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Discussion Starter #6
Sorry, one last question - I've read that replacing the DP with an aftermarket one can cause the CEL light to come on and cause issues. Is this something that can be easily fixed without doing any damage while working correctly?
 

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2009 2.5xt 6 Speed Swap version 8 6 speed sti trans with r180
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The Cobb Access port will take care of the lights. That's one of the benefits of the tune. There are other tuning methods but this is the most user friendly way to go about it albeit more expensive slightly.

So in Short: With the Accessport loaded up and the stage 2 tune selected you'll get no lights. They essentially shut that rear O2 sensor off and don't use the closed loop fueling which is what that sensor is there for. The O2 sensing will then only be done by the sensor in your Header coming right off the engine which is completely pre CAT no matter what.

There are small fixes for spacing out the O2 sensor and shutting the light off but I don't prefer that option or know much about it.
 

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2009 2.5xt 6 Speed Swap version 8 6 speed sti trans with r180
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Here's the pipe i'm referring to:
Catted Downpipe

There are plenty of other models but this one is best priced for the features which really only include the Extra O2 Sensor port on the bellmouth. Many of the higher priced ones don't include that option.

And the Cobb Accessport can be found here:

Cobb Accessport
Either the V2 or V3 accessport work fine. The 3 is just newer and fancier.

www.rallysportdirect.com Carries most anything you could wish for and usually ship quick, or you can go through many other online suppliers or local tuners.
 
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