matth76

Hi everyone
I bought my new Hawkeye STI WRX type UK with PPP last Saturday and have loved every day since buying it! This is my first Subaru (I've always wanted one) and love it! This makes up for the huge insurance and fuel bills!

Anyway my question is, what parts of my exhaust have been modified by Prodrive as part of the PPP? I have done extensive searching on this forum and on the internet as a whole and cannot find any exact info on this. Some say just back box and some say backbox and "down pipe" (I assume this means one of the cats has been removed). I assume the standard STI exhaust has two cats then, and if Prodrive has in fact removed one of them it keeps just one cat (to keep it legal).

I know it is definitely the backbox but is any other part of the mid section or cats been changed/removed? I am thinking of making it slightly louder (to get more of the burble) without it being too loud (just a touch louder) but still retain the parts Prodrive has put in. Please can anyone recommend what I can do? Could I remove the remaining cat (to keep things simple and cheap too)? Is the standard ecu just remapped by Prodrive or is it an ecu supplied by Prodrive? And is it possible to retain the ecu and have it remapped further to make the most of the decat? Is the "upgraded" fuel pump supplied by Prodrive a 255 lph fuel pump same as Walbro?

Final question un-related to above and not too important: done searching on this but found no results - how do you guys protect the blue "suede" part of the seats - do you spray it with suede protector?

Thanks for any help with this.
Cheers
Matt

mark@wrx

Taken from a media file "The extra power and torque are achieved by re-programmed Electronic Control Units (ECU) plus the removal of the rear catalytic converter, fitment of a high-flow catalyst and sports silencer. The Impreza WRX STI also has a new high-flow fuel pump".

cster

Don't think they fit a high flow cat, just remove the second one.
AFAIK, the rest is correct.

matth76

Thanks guys. Yes I had read similar on the Prodrive site although they just said "sports silencer" which I assumed to be the backbox but not much else, other than ecu. So all they have done is remove the rear cat, and fitted the backbox. And the ecu is the standard ecu but they have just remapped it. Does anyone know more about the fuel pump and what the flow rate is?

The alternative to me removing the remaining cat is to just replace the centre section with a bigger diameter stainless steel one, then get a further remap. Or would the removal of the remaining cat be more power effective (with remap) and give that slight bit extra noise (and just leave the centre section alone)? I know I would have the hassle of putting the cat back on come MOT once a year. I dont want to lose any low down torque - only gain it.
Thanks again for any help.

my06 ppp silver

iTrader: (2)

exhaust, depends on the year. mine, 06 sti, backbox only
seats, dont let the kids or missus eat and drink in the car, keep it tidy, job done.

carl heath

dont worry too much with interior its a car after all,and it can all be steam cleaned to new anyway,mine comes up really well.

matth76

Thanks guys. I've had someone else tell me that the PPP exhaust on the Hawkeye sti only includes the backbox, nothing else and both cats are retained, so quite a lot of conflicting info. I wish Prodrive would publicise what is included. Please can anyone confirm if one of the cats is definitely removed?

daz1968

iTrader: (13)

the hawkeye ppp has the backbox and a short sports silencer to replace the 2nd cat, I know this as I bought one to fit on my MY05 jdm as it is near identical to the jdm silencer as the jdm only has the one cat as stock, but was in stainless steel so I could remove the weak link in my exhaust, other than the exhaust should only have an uprated fuel pump and ecu recalibration. Not a lot for your £1600. best thing to try first is just replace the centre pipe with a deresonated straight through pipe, then if you want it a little louder change the backbox, Unless you want the hassle of changing the cat come mot time, a good remap will improve on the ppp if you want anymore performance from the car, just add a panel filter as well, not sure if a 3 port solenoid is worthwhile on a 2.5 sti , but I fitted one to my jdm before the remap.

matth76

Thanks Daz. Exactly the info I was looking for

So if I replace the centre section with a straight through pipe I will still retain both the standard first cat and the sports cat fitted by Prodrive as these come before the centre section? I could remove the first standard cat and put a downpipe and just retain the sports cat fitted by Prodrive although Im not sure one sports cat will pass mot. What's the bore diameter of the standard centre section? I believe Hayward and Scott do custom exhausts so I could ask them to do the centre section. My main aim (other than a bit more sound) is to improve the low down torque as much as possible and have heard differing stories of the effects of a decat - some say you always lose low down torque (although this may only apply to NA engines) and some say it's the best thing to improve it. Anyone know? Thanks again for all the help.

daz1968

iTrader: (13)

The second cat is removed only the one remains the replacement is a very small sports silencer. I have a Haywood and Scott centre on mine 2.5 inch is the standard bore. I think that would be your best first mod as it not only removes the resonator to increase the sound but it also being made of stainless will last a very long time compared to the steel one.

matth76

Do you mind me asking how much your Hayward and Scott centre section was? I like the sound of this and agree this will be my first mod. I assume a remap on top of this will not gain much and is not needed to keep things safe?

Oh I see, so the ppp keeps the first cat but removes the second cat and replaces it with a very small sports silencer. And the centre section then comes after this small sports silencer. I wish Prodrive/Subaru were more clear. The trouble I had last week with my insurance explaining it. Even I wasn't sure.

Thanks again.

daz1968

iTrader: (13)

Think the centre section was about £100 when I had mine but check on website for latest prices

matth76

I've booked my car in for this Sat to have the 2.5" straight through centre section. I assume the 3" centre section would be a lot noisier and have trouble fitting to my Prodrive backbox? I don't want it too loud but do want to increase low down torque if I can. Thanks again.