[CRJDriver10]

Hello

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

 

[2.5x_sleeper]

Are you retaining the CAT in the midpipe? If so, you could have a bung installed after that CAT & place the rear O2 sensor there with the $5 fix... just in case you need it. :wink:

Bobby...

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

 

[CRJDriver10]

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?

 

[2.5x_sleeper]

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?

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]

 

[CRJDriver10]

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

 

[2.5x_sleeper]

If you still have the CATted uppipe, you'll want to get rid of that. They can fail & pieces of it, ingested into the engine, can do serious damage! :icon_eek:

Bobby...

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

 

[2.5x_sleeper]

In answer to your previous question... what to do with rear O2 sensor, not that you need to know now, but here are the options: :wink:

• The $5 fix
• The O2 Foolers, The Economical, Electrical Way!!

► Disclaimer - We have the $5 fix on my son's '03 X & it works perfectly. I've never tried the electrical fix, so try it at your own risk. :icon_eek:

Bobby...

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

 

[CRJDriver10]

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

 

[Tweak3D]

@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.

 

[montanasuby]

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.