View Full Version : What exactly is the P1 standard exhaust system??

Andy E
31st August 2000, 22:05
How does the P1 exhaust differ from the UK Turbo and the STi??

The official line is that in the quest for European Type Approval, Prodrive "replaced the twin catalyst with a single advanced high density catalyst". Huh?

Does that mean it is different from the STi V or just different from the UK Turbo.

Does this mean a hi-flo cat and where is said single cat - downpipe or centre?

Lies, damned lies, and Prodrive?

31st August 2000, 22:20

No difference to STiV at all and one cat less (the middle one) in comparison to the UK one.


[This message has been edited by quattro (edited 31 August 2000).]

Andy E
31st August 2000, 22:25
So Prodrive didn't "replace" anything at all, they just kept the STi system in situ on the base car rather than have the usual twin cat system on UK Imprezas?

It doesn't sound like that, the way they tell it. To achieve euro approval they did two things: "replaced" the cat and aimed for acceleration figures that would give them an extra decibel to play with.

Puff The Magic Wagon!
31st August 2000, 22:51
Put this on Scoobynet FAO Simon Lines...

1st September 2000, 10:11
Definitive answer time.

The catalyst looks the same as any other Impreza cat externally, but has a high precious metal content (read more expensive)which makes it efficient enough not to need the second cat in the centre section to pass Euro emmissions regulations.

The centre section is the same as the one used for our performance package and the rear silencer is the std STI part.


Andy E
1st September 2000, 13:32
Excellent! At last an answer straight from the horse's mouth (sorry, Mike).

So, the P1 isn't just a rebadged STi.

I've read so much on the net from Impreza owners - esp. STi owners, strangely http://bbs.22b.com/ubb/smile.gif - casting doubts that Prodrive didn't anything other than add some badges to the MY99 STi V and marketing prowess to create the P1.

Those of us who own one can of course watch the video. The suspension mods are readily apparent, but perhaps you can put another ghost to rest...

What exactly did Prodrive & FHI do to the STi ECU. Extensive remapping or not?

4th September 2000, 12:15
The ECU was modified to meet EU emissions tests and still retain the 280ps as tested in Japan.


Andy E
4th September 2000, 16:22

Thanks. That's understood. But any idea what modifications were made? Or is that a big secret? http://bbs.22b.com/ubb/wink.gif


4th September 2000, 17:18

They were fuel and ignition mapping changes in some of the areas that affect the various emissions tests.

Hopefully this answers your question?


4th September 2000, 19:09
So you leaned it out at idle.. and at about 3K revs ? http://bbs.22b.com/ubb/wink.gif