PC555

Hi

Can anyone please confirm the number of cats I have on my MY53 STi after just having the PPP fitted?

If, as I've been told it's just the center cat, would removing this require an ecu remapping?

Anyone out there with a STi8 done this? and what difference does it make running a full de-cat?

Sorry for all the questions. I'm out of my depth ..


Cheers
PC555

PC555

btt for the morning rush

PC555

bump

greasemonkey

There's no such thing as an "MY53 STi" chap. MY stands for model year, and yours will either be an MY03 (aka STi9) or, (if it's very recent and has a square boot lock), an MY04 (STi10).

AFAIAA the post-PPP MY03/04 cars still have two catalysts, in the downpipe and centre sections. The PPP replaces the standard downpipe with an open neck one that contains a high-flow sports cat.

If you did remove both the existing cats, you'd find the engine would pull better again, and while you might not need to have it remapped, you might have to play around with the actuator restrictor bore to prevent transient overboost (aka spiking).

However, the downsides would be instant invalidation of your warranty, and non-compliance with emissions standards should your car be stopped and tested at the roadside, or, eventually, MOT'd.

You'd probably still pass an MOT if you removed the centre section cat, but the warranty issue would remain, and the performance boost would be nowhere near as pronounced.

PC555

cheers for the info.

I was under the impression that MY03 was the 1st reg of the year and MY53 was the second.

greasemonkey

No, that's registration plates, totally different thing! 03 is the index number prefix given to cars registered for use in the UK between March and August 2003, and 53 is the prefix given to cars registered UK between September '03 and February 04, there's no more, or less, to it than that.

The model year is the physical specification of the car as defined by the manufacturer, see the difference? In other words, all Impreza STi Type UK's supplied by Subaru to the 2003MY specification will have the same physical design, colour options, looks, basic performance, basic features and parts commonality.

PC555

Cheers mate. Thats certainly cleared up my misconceptions.

Still can't decide if the decat is worth doing though!

greasemonkey

Up to you at end of day, but, if I were in your shoes, given the age of the car, that you've already spent extra on the PPP, and that it'll have greater PX value through the dealer chain if you retain the warranty, I'd probably leave it how it is.

If you want to make it go better, next thing to do would be the spring kit.

PC555

already done the spings and bigger wheels

JohnD

iTrader: (5)

PPP on the STi removes both existing cats and replaces the downpipe one with (as Greasemonkey says) with a high flow item. So you finish up with just the one in the downpipe. The centre cat is replaced by a pipe (with lambda sensor and original heat shielding retained) The original resonator in the next section along is retained, and of course the back box is replaced.
JohnD