ScoobyRalph

Ok so i know the PPP pack is basically a free flowing exhaust, panel filter and a map and most people talk of a similar combination of items for non PPP cars.

So i have a stock '03 STi and want to know whether there is any mileage in replacing my panel filter, retaining the stock exhaust and having a remap - will this see much gain??

The reason i ask is i don't really want an aftermarket exhaust, if it means i have to buy a decat or similar then i would prefer that. If i can achieve good gains with the stock system then excellent.

Would welcome any input on this.

Si

Gigsy

The benefits of a free-er flowing panel filter have been debated - some say it makes a differences, others say just replace your paper one more regularly.

As far as a remap goes, yes you should see some decent power gains without needing the full PPP bits (STi PPP is a replacement backbox, decat center pipe, uprated fuel pump and a sports cat downpipe). Having said that, I'm not sure where the STi is in terms of requiring a more powerful fuel pump, I have a feeling it's close to the limitations of the stock one so if you do get it mapped, it would be a good idea to upgrade the pump.

A decat center pipe should be no more than £100 and 2nd hand ones can be had for half that. I would consider doing that rather than spending £40 on a panel filter as it should see better gains than the panel filter.

A sports cat will allow further gains but obviously the costs start going up at that point.

ScoobyRalph

Thanks Gigsy that's really informative and exactly what I was after finding out.

I didn't realise the PPP included down pipe and fuel pump - very few people list that in their ads from what I have seen. I did wonder about the panel filter, can't imagine they vary that much but asked because it seems whenever someone uprates parts and maps they always do a panel filter.

I am glad to hear that taking into consideration an updated fuel pump and a decat centre section I could see some good results. I want to keep the car completely standard in appearance hence not wanting to replace exhaust etc.


I will have a look around for some centre sections and make enquiries into a fuel pump.

Thanks again, very helpful.

Si

Gigsy

It's only the STi PPP pack that includes the downpipe and pump... the WRX PPP is just the decat pipe and backbox which might be why it's not listed?

Both STI and WRX PPP kits also include a silicon Y pipe from the turbo to the intercooler. I found replacing the stock pipe with one of these helped the engine breathe better at the top end - not sure if there is any performance gain but again, it's cheap and easy to change (and won't change the stock appearance ).

As for panel filters, mapped gain between K&N style and stock paper filters is reputed to be around 5bhp... every little counts of course but like I say, if it was one or the other, I'd definitely decat the centre pipe over changing the panel filter.

IIRC, Cobra make the new range of Pro-R exhausts - I think they sell decat center pipes via eBay for c£60.

Re fuel pump, the most popular is the Walbro 255. Do you have a mapper in mind? If so, it's worth giving them a call and asking for their advice on fuel pumps, like I say, not 100% sure of the fuelling requirements on an STi over a WRX.

ScoobyRalph

Ok that may explain the omitted items in that case. The y pipe sounds another good improvement, will do some further reading into that.

Think I have found a suitable decat, will PM you the details in a mo to check its the right thing.

As far as mapping goes I am not sure who to take it too, read a lot about JGM and Bon Rawle but would probably look to take advice on it really?? I an based near Bristol so I guess geography plays a part.

Si