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2004 Forester XT
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Discussion Starter · #1 ·
Hello

If I go with a catless downpipe, what do I do with the o2 sensors? 2004 FXT
Thanks in advance
 

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2007 Forester Sports XT 4EAT
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Discussion Starter · #3 ·
Thanks for the quick reply, the downpipe I am looking at is fully catless, where would the front o2 sensor go, how do you eliminate the rear electronically?
 

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2007 Forester Sports XT 4EAT
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The front O2 sensor on your '04 is positioned on the exhaust manifold, ahead of the CATed uppipe.

So that CATless downpipe you're installing will replaces both rear CATS... downpipe CAT & midpipe CAT? :confused:

You are aware you won't pass emission testing if you're entirely CATless.

Perhaps the attached exhaust diagrams will help. :wink:

Bobby...

'04 XT


['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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Discussion Starter · #5 ·
I am probably going with a catted downpipe. I did some research and I think the wife is ok with mods but not so much the gas smell.
Thanks
 

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2007 Forester Sports XT 4EAT
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Discussion Starter · #8 ·
Just ordered a Grimspeed catted downpipe and Grimspeed uppipe, I figured order good stuff and do the job once, can you suggest a catback option, either aftermarket or OEM that will better( but not too loud) than the stock FXT? Also thanks for the great advice as far as the uppipe, I think that's the main cause of my troubles. I think I might of caught it early, when I do these mods I am going to inspect the turbo. I was looking at 20g Twisted Motion sells, these seem to hold up well, any suggestions?


Again Thanks for the great help.


George
 

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2017 Forester XT Touring
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@George Altamirano what are your goals with the car? can't really recommend much until we know what your vision is. 20g will work, but you'll likely want a new intercooler, fuel pump, fuel injectors/rails/lines and possible some transmission work depending on if you are a manual or auto.
 

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2004 XT 5 MT
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I am probably going with a catted downpipe. I did some research and I think the wife is ok with mods but not so much the gas smell.
Thanks
A catted down pipe still allows you to get good horsepower and torque and still be loud if you desire. An sti takeoff cbe is a good starting point for rear exhaust coupled with your current dp. Or cobb or other dp.

I will say I got a stromung turbo back exhaust from boxer 4 racing and I’m still happy and impressed with it years later. It’s just loud enough for the wife to still want to drive or be in car. I wouldn’t want to go on a super long road trip with this exhaust, whereas when I had the sti cbe it was only really loud when you were pushing it.

Lastly,FYI, these cars are infamous for gas smell from the rubber gas lines under the intake. If yours are original this could be a problem if not now then in the future. If you repair them use the OEM Subaru hose, the parts store hose isn’t the same metric, exact, size.
 
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