05 WRX wagon PPP up-pipe
 

I've got a fully stock 05 WRX PPP hatchback, on just over 110k miles. I've been reading about replacing the up-pipe to a de-cat one to avoid damaging the turbo. Just a couple of questions to someone who might have experience with this. Will I need a remap, considering it already has the PPP remap, around 260hp? I'm not really looking to increase power yet, just want to be safe. Will it still pass an MOT, as I understand PPP removes the 3rd cat on the standard WRX, and removing the up-pipe cat will leave it with 1 cat. Will I have any problems if I just replace the up-pipe and not remap, but still use the egt sensor to avoid a CEL?

Thanks in advance!

It's definitely worth changing the pipe to an sti oem one and definitely worth getting the remap after.
will be best 300 you can spend on the car if you have an open source remap.
will still pass the MOT. Mine did anyway.

He written precisely that he has PPP map, not the custom open-source one.
@bradcav I don't know mate, I am in the same boat though (I have 2004 PPP ecu and a decat uppipe waiting in my basement). Some people say you cannot do this without remap and other say it's not that big change (like changing downpipe to a decat version) and ecu will be fine with that. They say that the only reason to tweak ECU would be disabling CEL from missing EGT probe, which can be easilly fixed by a resistor mod.
As a side note, I know one guy who has 05 wrx ppp and he changed full exhaust to prodrive version (including downpipe) and he has driven his car for 2 years without a remap and had no problem so far.
I am going to replace my uppipe with a decat version without a tune, but this is distant future.
Change it and give us a report how it goes. Or change it together with a downpipe and go for a custom map.

I assume I won't get any CEL if I re-attach the temp sensor, as long as the new up-pipe has a bung for it (the ones I'm looking at do). I can't imagine a custom remap will make much difference and I don't really want to pay for one to only gain maybe 5-10 hp, however in the future I will go full sports cat turbo back, better intake and fuel pump etc and get a remap when I have those parts. I'm hoping I can just swap out the up-pipe to avoid risking it failing, since it's quite high mileage, without damaging anything by not tuning.

You can't refit the EGT Sensor into the STI up-pipe, there's no bung for it. You can either fool the ECU by putting a resistor in the plug (google it) or have a map done which turns it off.

I have a set of sti headers and de-cat up-pipe for sale atm.

I'm looking at the hayward and scott one on scoobyworld, it looks like it has the EGT bung in it? What's your thoughts on running a decat up-pipe with the PPP factory map until I've done more upgrades and get a worth while map? cheers

I can't understand why you want to do it now if future upgrades are planned. As said on you're other thread the up-pipe cat is at risk from overheating only when the exhaust has been de-catted further down. Any increase in performance without a map is risky, probably from over boosting which you wouldn't know unless running a boost guage.
My penneth, resist the temptation until you're ready.
Trev

I just want to play it safe, but if there's minimal risk that the up-pipe cat will fail since there are no other mods to the exhaust or engine, I'll take your advice and do the whole exhaust, intake fuel pump and remap in one go. Since I don't want to up the power just yet, I guess I'll crack on with suspension and brakes, maybe a cat back until I'm ready for more. Cheers for the advice, really helps out a scooby nooby!

here's a copy of what we posted on the other thread............

in general there can be issues with the up-pipe cat IF you have de-catted the rest of the system and it overheats

we manufacture / supply the Harvey Smith range of "trick" up-pipes and specifically make a variant to suit the small TD04 your car has fitted

we always recommend at least a map check but you will get more benefit from a custom map to take advantage of their benefits