I'm going fit a de-cat up-pipe fairly soon, and I was wondering how quickly I'd need to get it mapped afterwards. Would it be a good idea to fit one of these:

http://pages.ebay.com/link/?nav=item...706201&alt=web
Has anyone else used one?

 

Do you still have the CATS after the turbo? Decat up-pipe doesn't require a remap (although will benefit) neither will it throw a Lamba code AFAIK.

 

My wagon has got the standard PPP exhaust, so I believe it's got one high flow cat after the turbo.

 

You will however have to do the egt fix...................

Above the pre-cat in the up pipe is the egt sensor which you won't have/need if there's no pre-cat.
Item 17




A 2.2K ohm resistor across the terminals of the vacant connector will prevent any cels occurring.

http://www.clubwrx.net/forums/engine...istor-mod.html

 

That's a great tip, link and info, thank you very much! All I need to do now is change the up-pipe. From all I've read on the interweb it sounds like a proper PITA.

 

As yours is a WRX PPP, I think you may have got the wrong info regarding what comes in the package.


For the WRX you get the following...

Recalibrated engine
management system
•
High flow intercooler hose
•
Stainless steel sports
exhaust silencers
•
Only available as a
complete package -
components cannot be
bought separately
•
Certificate of fitment to
enhance resale values

For the STI you get the following

Recalibrated engine
management system
•
High capacity fuel pump
•
High flow catalyst
•
Stainless steel sports
exhaust silencers
•
Only available as a
complete package -
components cannot be
bought separately
•
Certificate of fitment to
enhance resale values




The 05 WRX varied only slightly from the 03-04 WRX setup

<a rel="nofollow" href="http://imdomino.imgroup.co.uk/IMGGB/WWW/Subaru_Accessories.nsf/NULL/FCF6E8E3044B3D2280256DDD00399AB7/$FILE/03MY%20WRX%20PPP.pdf" target="_blank">WRX PPP

 

I have a Wagon with PPP and it has cat in the up-pipe, and 2 cats in the down pipe.

Not a lot of point getting it mapped if you don't remove/replace the cats post-turbo.

 

By jove you're right. I thought the center cat was taken out, but that is just an sti. So, time to find a decat center section...

 

the second cat isn't in the center section, it's in the bottom half of the downpipe. Standard downpipe has 2 cats in it one pointing vertically and one horizontally so you can either get rid of just the second cat (2nd cat delete pipe off a prodrive STI or from ebay/scorpion etc) or replace the whole downpipe with a sports catted downpipe for best results.

The center section has a box in it, it's just a resonator to kill off the sound so if you replace that with a straight through section with or without the cats you'll get a bit more note out the back.

 

Right. I'm proper confused now. So i thought the car had three cats. A pre cat in the up-pipe, one in the down pipe and a scrubber cat in the center section.
I thought it would be a reasonablly simple mod to remove the pre cat, in the up pipe, to improve spool and reduce the chance of the cat degrading and killing the turbo.
Should I instead get rid of both the pre cat in up-pipe and the down pipe and just leave the scrubber cat, or some other combination?

 

The cats are items 15 and 29 in the previous drawing

The centre pipe is only a resonator

Just for clarity



You can remove the second cat (marked 1 above) without needing a remap or effecting MOT.


2nd cat delete pipe


available from most exhaust suppliers.............

 

That was the photo I was going to post. A decatted up-pipe helps increase spool rather than power. It's not needed for mot. The 2 cats after the turbo are the ones that strangle the power and need to be sorted in order to make a remap worthwhile. If you fit a sports cat downpipe, it will be one single pipe that replace both.

 

You two are great. If I ever meet you I'll buy you a beverage of your choice. Thanks for taking the time to help a noob.

 

05 wrx ppp doesn't have item 1 cat in the diagram.
It still has the heatshields which makes it look like it has a cat but if you remove and look there's no cat in there.
Not sure what year it changed but my 05 ppp wagon wrx doesn't have it.

 

Think I might have one of these Stuart if you want one (and could probably get it to Cambridge), let me know?

Cheers,
Paul

 

Thanks for the offer. I'd definitely be interested, I can see new scorpion stainless ones are about £90 delivered from ebay, but I'd always rather get one from here.

 

As mentioned above, looks as if you have the 2nd cat delete pipe already - quids in

WRX ppp

 

I'm going to get under the car tomorrow and work out exactly what I've got, before I go and buy any more parts. I'll try to get some pictures when I do. It's a 10 year old car so it may have had some changes I'm not aware of.

 

Like I said, the pipe still has the heatshields on which makes it look like it has a cat in it.

 

Right then. I've just had a crawl under the car and tried to take some pictures. This is the best.



I can see some heat sheilds, but if I look in the crack between then I can't see a cat. Am I looking in the right place?
Another point is that this section in question looks newer than the rest of the exhaust, if you look at the flange on the right of the picture this section is a lot less rusty.

 

Yep - 2nd cat delete pipe fitted

 

So based on this, is changing the up-pipe for a de-cat version a worthwhile mod? And will it then land me in trouble come MOT time?

 

Worthwhile (better spool up) and no, MOT shouldn't be a problem, you still have your main cat.

 

Thanks for the advice.