How many Cats does the MY02 STi7 have? Is it just a downpipe cat?

The reason I ask is that alot of used STi7s here have decats from the turbo back. With the recent threads this sounds like it has the potential to break things due to overboost or even worse lean running. Supposedly overboost doesnt happen with some of these exhausts.

Does a decat only produce more power by running leaner (assuming there is no overboost)? The boost does seem to come in earlier on a decatted car but why?

If you only change the center and back box is this a safe option? Would you only get more power due to running lean or running closer to the ideal AFR? It appears the PPP is just a piggyback with boost map, if this is true then a center and backbox change should be as safe as a PPP?

Kinda taking this further,


If swap my PPP Centre and Backbox with a Blitz Nur Spec R, will this cause any probs with the STi7 ?

Where's Big Goon gone when you need him....

Nope :D ;)

If you're about you can have a listen to mine :)

SammyH,

Naw, you've got a Nur Spec?


Swine! [img]images/smilies/mad.gif[/img];)

Was the Fitment ok?

Perfect :D

Did you need any extender pipes?

b5m, The STI UK has a 4 pipe configuration from the turbo back.
The first is the downpipe which has a cat, the second (1st mid section) is a resonator, the third (2nd mid section) is another cat and then leading onto the backbox. However the mid sections maybe the wrong way round. :rolleyes:

On the PPP they have replaced the downpipe with a sports cat, kept the resonator, replaced the 2nd cat with a straight through and replaced the back box. Also replacing the restrictor because of boost spikes I presume. The ECU has a daughter board installed acting as a boost controller which AFAIK holds the boost on longer giving more torque. Anyone please correct me if I'm wrong.

Various tests have been done by different people on the STI 7's in regards of exhaust changes, the outcome was boost spikes were evident if you change the downpipe/up-pipe(cured by a restrictor), however leaving those standard and changing the mids/backbox standard boost applied. Again people in the know correct me.

I cannot see any problems from changing the mids/bb however IM see it differently but IMHO they have to prove that an engine failure was caused by the exhaust, but that's another story in which I will voice my opinion. :)

Rob.

On my STI7 I have no PPP, but have the PPP centre and tail-box.

Makes the car run far better and sounds nice too. AFAIK the boost stays the same but until I have a guage I cant tell. Dave TS can tell you more as he has been through all the combinations....

Ids

Does changing the centre section and back box improve turbo spool up? The standard STi has very little torque and power below 4000rpm. I am fairly sure changing the downpipe will but that is more risky.

In my opinion, i think it makes a noticable diffrence.

if you get the chance to try a car thats had it done i think you will notice too. Mine now picks up at about 3.5k and really goes all thru the rev range right up to the limiter.

ids