[Scarvix]

I have a 2004 subaru wrx do these come with a catted I pipe or catless also if I get a catless invidia upipe will it affect my emissions?

 

[zax]

catted and yes - will impact emissions

 

[Scarvix]

catted and yes - will impact emissions

Thanks bro I’m just going to stay with oem. Got any advice for my car right now I have a Cobb catted downpipe with custom catback, Cobb intake sf, Cobb boost solenoid, and accessport trying to keep my car at a safe horsepower build but also want a little more or do you think I should keep that setup

 

[zax]

Let me ask you something... when you asked "impact to emissions" were you asking about whether the modification had an impact to the overall emissions of the vehicle or were you asking about whether it would "pass a state emissions test?"

 

[Scarvix]

Let me ask you something... when you asked "impact to emissions" were you asking about whether the modification had an impact to the overall emissions of the vehicle or were you asking about whether it would "pass a state emissions test?"

If it will pass state emissions

 

[zax]

If it will pass state emissions

I don't know your state's emissions testing regiment.

Here in Maryland, my WRX always passed state emissions testing with a catless UP. You must perform the resistor modification to clear the CEL if you eliminate the EGT sensor (recommended). We used to have visual as well as ECU testing. Most techs would have no idea there is supposed to be a 3rd catalyst in the UP and therefore don't look for it. Technically it is federally illegal to remove.

I typically don't advocate for deleting emissions equipment HOWEVER the UP cat in the 2002-2005 WRX was an exceedingly stupid kludge design to bring the WRX stateside. It kills turbo spool and provides material that can act as projectile vomit into your turbine.

 

[XJman]

This is just from reading, so take it with a grain of salt.

Most states it will pass as they don't do anything besides check for codes and look at the bottom of the car. If they do tail pipe testing, then it's about 50/50. People have passed one time and failed others. Or failed at one testing facility and passed at others.

My honest opinion, old cats can degrade and send the substrate into the turbine. Catless uppie is the way to go.

 

[zax]

I recall that the up-pipe cat was mostly used for cold-start emissions where the rear cats can't reach light-off temps fast enough being so far from the exhaust header. When at operating temps, the up-pipe cat shouldn't contribute much (if any) to overall emissions. This was accomplished in later cars with secondary air-injection.

If that theory is correct, even tailpipe sniffers shouldn't fail a car with a catless up-pipe assuming it has been properly warmed.

 

[CalvinT]

I have a 2002 WRX which also came with a catted up-pipe. I replaced it with an STI up-pipe which doesn't have the cat. I used the STI up-pipe because I knew there'd be no fitment issues and no problem with the expansion joint. Plus it looks stock and not aftermarket. To keep from throwing a code replace the probe with a 2.2K ohm 1/2 watt resistor.
I can send you one free.

 

[CalvinT]

The Subaru part number for the STI up-pipe is 44614AA000. It was also used in turbo Foresters and turbo Legacys or any other Subaru of that period with a turbocharged 2.5L engine. It's still available from Subaru for over $400, ouch!

 

[WTypeRogerX]

We have CA emission dyno tests as well as visual inspection. On my 2005 WRX, I replaced the uppipe with an STi uppipe and replaced the rest with a TXS exhaust (downpipe, high flow cat in the mid pipe, and muffler) that passed emissions for 12 years. When the high-flow cat finally failed, I had it cut out and replaced it with a different aftermarket cat that passed emissions.