Hi

Just got my My03 STi PPP.
The back box has been replaced with a non PPP aftermarket one but at the moment I'm not sure what type it is.

Will replacing the backbox have any negative effect on the power from the PPP?

If I want to get a proper PPP box are there different types, different partnumbers between STI and WRX ppp boxes?
Are the PPP boxes the same as WRSport backboxes that are reguarly on ebay?

One more question. I have tried a search on this but can't find the details I want. I understand that the PPP replaces one (or more) of the cats. Which one?. Is the downpipe changed? Are the replacement parts marked with prodrive? Basically, how can I confirm if the exhaust on the car is still the PPP kit or been replaced again since?

Cheers
Steve

 

The STi PPP consists of a replacement downpipe with a high flow cat. If it was done pretty well when the car was new, here should be a heat wrap around the cat section of the downpipe. The second cat. is replaced with a straight through pipe, but may have the original heat shielding replaced as it protects the sensor that is in this section. The third section is part of the original system and is a resonator. The final part is, of course, the backbox. I would have thought in your case, this has been replaced just to get more noise! There really is no other reason to swap the Prodrive box, it's as straight- through as any other after-market box.
I doubt very much if you'll notice any performance difference by putting back a PPP box (or WR sport box - only difference is the oval tailpipe) but you may notice a reduction in noise.
JohnD

 

Do you have the PPP certificate?

 

Change the centre section to a unresonated one along with the back box and you'll certainly notice the difference.

It'll not really give you more power but it certainly helps with the spool up and seems to result in less lag.

Port the headers as well and it'll help with the effect even more so.

 

Thanks for your replies

53WRX - Yes I do have the certificate.

JohnD - Having looked at the downpipe it does appear to have heat wrap around the cat itself. Also the neck (where it meets the turbo) appears to be the open mouth type incorportaing the wastegate (is that right?). Will any of the parts which have been replaced have prodrive written on them?

Anyone interested in a swap for a PPP backbox for a louder one (will confirm make)?

Cheers
Steve

 

As far as I'm aware, only the back box has Prodrive identification on it.
If the downpipe is of the open mouth design, then it's the later version. Mine was fitted in Sept. 03 and has the seperate wastegate pipe feeding into the main downpipe body.
Replacing the resonator section with a plain pipe section (eg TSL approx. £100) will increase the noise level a tad.
JohnD