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2004 Forester XT
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13 Posts
Discussion Starter #1
Just read a thread back from Feb that mentioned changing your uppipe for Stage 2 so Cat doesn't detonate and destroy your turbo.

Regardless of whether I restated that right...

1. Can/Should you replace your entire exhaust system and remove your Cat?
2. Is it legal to not have a Cat?
3. Will I pass emissions testing without a Cat?
4. Does the Stage 2 Exhaust system (3") somehow reproduce the function of the Cat or make it unnecessary?

Thanks... you can see I'm confused...

Walt
 

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2004 Forester XT Premium 4EAT
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The uppipe cat is expendable and only exists in the earlier XTs (04-05) for cold start emissions reduction. Other than that, it does nothing. The more recent models no longer have a cat in the uppipe (it was replaced by a smog pump in the engine bay).

Is it legal to remove a cat? Technically, no. Will you pass emissions? With absolutely no problem. You can replace it with a catless uppipe from a later year that retains the stock look and heatshielding if you're worried about not passing visuals, but the uppipe is pretty hard to see anyway.
 

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2005 Forester XT 4eat
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In addition to what Silke says, stage 2 and up-pipe replacement are not the same thing. Stage 2 on our cars typically refers to replacement of the turbo-back exhaust, which includes 2 cats, and is not legal. You can get away with it in a lot of places, but not California, and nowhere where a strictly enforced visual inspection is mandatory.

You can get a turboback exhaust with a cat, but it does not make it any more legal. If the emissions testing in your area is strictly OBD-II, then you won't have a problem passing, even though the exhaust is technically illegal.

If you do install a turboback exhaust, you need to run some kind of engine management to prevent the risk of engine damage, and to make use of your modifications.
 

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2004 Forester XT
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Discussion Starter #4
Thanks!

When you say "Engine Management", do you mean a new ECU Map?

I live in Missouri (even if I move, it won't be California) and have an '04 FXT. No mods so far. Not sure about my state's emission procedure. If they find an illegal exhaust, do they call the cops or just flunk you, or what? I assume the best bet is to keep the stock exhaust to replace it if necessary for emissions testing or if you get busted...?

I'll probably start with Stage 1 when I have enough money for an Accessport. If that smooths my idle and gives me some extra torque and HP, I'll be happy.

But please give me your advice as requested above...

Thanks,

Walt
 

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2005 Forester XT 4eat
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Yeah engine management means a way to remap the ECU. They won't call the cops on you if you fail an emissions test. Keeping the stock exhaust is what I plan to do, but I'm pretty sure that most people can pass the emissions tests with a turboback exhaust.
 

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2009 Forester XT Auto
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218 Posts
So while we are on this subject.

I know what smog pump sounds like when the car starts, I never hear it on my XT so it is safe to assume I have an up pipe cat then.
 

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So while we are on this subject.

I know what smog pump sounds like when the car starts, I never hear it on my XT so it is safe to assume I have an up pipe cat then.
All of the pre "facelift" XT's have the uppipe cat (04/05) in 06 they went to the air pump setup, you can tell my looking under the hood, theres a black plastic almost "turbo" looking device on the left hand side of the car between the master cylinder and the battery. Can also tell by looking at the actual uppipe, if it has a sensor in it, then it's catted.
 

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2016 Outback and WRX CVT
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Is it legal to remove a cat? Technically, no. Will you pass emissions? With absolutely no problem. You can replace it with a catless uppipe from a later year that retains the stock look and heatshielding if you're worried about not passing visuals, but the uppipe is pretty hard to see anyway.
^ +1.

For the visual, a gutted cat. (or cat.s) is the best way to go, but as pleiad7 said, it's gonna take one heck of a well-knowledged tech, looking specifically for the UP cat, to notice that it's gone.

What's actually below the car, in terms of the last cat downstream of the turbo (the immediate post-turbo cat is also hard to see, and with any sort of a turbo heat-shield in-place, it's again very well covered, and will require the pursuit of a knowledgeable technician), is the one that's most easily seen, and most routinely checked during the visual component of any emissions check, typically with an under-car mirror. Again, either gutting the factory cat or welding a faux cat-cover in-place is the most surefire way to go, however, most technicians in anywhere but the most strict areas will typically accept what obviously looks like a high-flow/performance cat.

This is all very variable, and will depend not only on your local area, but your local techs.

Typically, well-tuned "Stage II" Subarus, even ones that are completely catless, will pass an idle sniffer test, along with the usual OBD-II check (given that your engine-management system both obscures any CELs as well as cloaks enough non-ready states), without raising any flags whatsoever.

Most municipalities in the States do not have the AWD-dynos needed to "treadmill" an AWD vehicle.

And as to what they'll do to you, vroomvroom?

I honestly doubt that they'd give you a ticket - or, for that matter, call the authorities on you (although I don't know about Cali! :wink:). Where I live, it ranges from a wink and a pass to a twenty under-the-table to just a printout of the car's failure status, and a re-test.

My "Stage II" '05 LGT's eCheck (our emissions check) came due this past winter. She's without both the pre-turbo cat. as well as the immediate post-turbo cat., but I've retained the last cat. for "civility," for my wife, who has had to deal with my catless DSMs for way too many years as my girlfriend. :smile: My engine-management is ECUTeK, tuned by Tim Bailey of PDXTuning/SurgeLine.

She easily passed.

The tech didn't even do an under-car visual on my Legacy (although, for my wife's then '05 WRX, they did break out the mirror - go figure? as the WRX was bone-stock), and as for the OBD-II scan, the ECUTeK overlay meant that there were no CELs/DTCs (active or pending), and all my sensors popped up ready.

:smile:
 
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