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Discussion Starter #1
Curious as they appear to be changing the rules in STX- you can still run just one cat BUT now they say you can't have CEL's, NOR can you run a "fix" to override the cel (mechanical or ECU).

is anyone running a catted downpipe W/O any cel "fix" and staying P0420 free?

I'm currently running catless shorty w/ the 3rd oe cat in place (which used to be "legal")- my new strategy is to run a catted shorty w/ a 3rd cat delete IF the high flow cat is effcient to keep the P0420 at bay???

TIA
 

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Discussion Starter #3
supposedly there is a "gentleman's" agreement not to protest anyone on this- I guess we'll see. I now some folks have already made the switch (at a pretty steep $)- one fellow is running a catted downpipe into catted a midpipe w/ the O2 sensor run at the back end- that MIGHT be a little overkill if one cat will do the trick :)

I know Prodrive, Helix, Daddy's, Invidia all offer a catted downpipe- who else am I missing?
 

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I saw that. I googled the exhaust but couldn't find a link. That stuff is pricey.

I also looked and Cobb has revised STX maps that do not disable the CEL's. I need to get a working EGT probe in my gutted uppipe, and then I will be installing this map to see if it throws any codes. I'd really rather not have the EGT probe in there, but we will see what happens.
 

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Discussion Starter #7
I'll probably have to gut mine as well- currently running a STi uppipe w/ no provision for the egt. If I read the "clarification" right an egt probe is now a must. Damn their clarification anyways- things were fine for five years and all of sudden the rules change
 

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I'll probably have to gut mine as well- currently running a STi uppipe w/ no provision for the egt. If I read the "clarification" right an egt probe is now a must. Damn their clarification anyways- things were fine for five years and all of sudden the rules change
Yeah, I don't see anyway around the EGT probe. If you need an extra uppipe I have one. I may get a new EGT probe as mine is hacked up. I called King of Parts and they have them in stock for about $45ish.

Once I get a working one of those, I can load up the revised STX map and see if the O2 sensor in the DP throws a code. If it doesn't, I'm golden. I'll be crossing my fingers. :sadwave:
 

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Discussion Starter #9
thanks- still have my original one :)

if your downpipe is not catted, the chances of not throwing a P0420 is very slim- it may take a couple of days, but will eventiually throw it (this was my experience anyways). Early on before there were many fixes I even had a exhaust shop move the O2 bung on the 3rd cat so it sat behind it- hoping the 3rd cat was effcient enough not to throw the cel- lasted about a week (thought I had skun a fat hog at the point :D), but the damn thing then came on :(

I've since gone w/ a ECU fix which obviously works like a charm- or did until this "clarification" came out :)

Mike
 

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I run the catted Invidia DP and I've flashed Cobb's standard stage-2 mapping.

I know P0420 is one of the codes "defeated" by the AP. However, I'm not sure what that really means. Does the AP just keep the CEL shut off despite the code, or does it keep the code from getting set in the first place?

I've scanned my '04 WRX for codes with both the AP and another OBD scan tool. Both interfaces bring back zero codes.

Does this mean that I've successfully avoided the P0420 code by running a catted DP or does it mean the AP is just doing its job?

I guess the former would be good news for you autocross junkies, but the latter would be no help at all.
 

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I also have the Invidia catted DP. The AP defeats the code from occurring. The sensor may be creating a signal that should normally trigger a code, but the AP map does not allow that code to happen. SO... there is really no way of knowing if you will get a code or not until you remove the code defeat in the AP map, which Cobb has done with the STX v1.32 maps.

As I said, once I get a functioning EGT probe in the car, I will load up these revised maps and see if my Invidia catted DP is "up to snuff". If it is not and I get a CEL from the rear O2, I guess I will have to try other downpipe options.

Joy.
 

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I have the TurboXS catless downpipe but a catted Midpipe w/ the sensor in, and I never threw a CEL for it. I have an AP, but even before I reflashed I never got a CEL.
 

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Jay- ahhhh you've already got a catted downpipe- I'll keep my fingers crossed that it works :)

downshift is this a aftermarket 3rd cat that relocates the O2 sensor after said cat? If so which one :) That would be an even better (read cheaper) option as I could keep my current downpipe

I know for certain that any catless downpipe combined w/ oe 3rd cat (which has no influence at all on the P0420 as the O2 sensor is UPSTREAM of it) will throw the cel- it may not immmediately, but it will.
 

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Jay- ahhhh you've already got a catted downpipe- I'll keep my fingers crossed that it works :)

downshift is this a aftermarket 3rd cat that relocates the O2 sensor after said cat? If so which one :) That would be an even better (read cheaper) option as I could keep my current downpipe.
Thanks.

The midpipe that Chris mentioned is made by TurboXS. However it will only mate up to the TurboXS downpipe which isn't catted. :sadwave:

I'm thinking that my backup plan my be to have a second cat welded into my Invidia DP. We'll see.
 

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From their website -

"MadDad(TM) Metal downpipe. You'll benefit from ..., and no-cels operation even without engine management or mil eliminators."

I have the DP specified, but am running EM.
 
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