The UK/Euro spec MY01 WRX (not the STi) has 3 cats as standard;

uppipe
downpipe
centre-section (in front of the resonator).

The Prodrive PP removes the third cat.

The downpipe cat is monitored for its "efficiency" using the two O2 sensors (wide band before it, narrow band in the centre-section before the third cat). Removing this will give you a CEL unless you get a fix box.

IMHO, removing the uppipe cat makes the biggest difference on an MY01+ as it allows quicker spool up and keeps the EGTs down. However, on the classic shape the improvement will be less as you don't suffer a cat in the first place.

Duncan ;)




[Edited by BugEyed - 7/2/2002 2:18:29 PM]

Please tell me that they are NOT the same thing!! :eek:

Mikey :cool:

up pipe feeds turbo, downpipe takes away from turbo.

The up pipe comes from the Exhaust manifold to the turbo, the the down pipe comes out the other end of the turbo and goes to the centre section of the exhaust.

Hope that helps,

Tony.

Damm, second best :( .

Advantages to fitting a "better" Uppipe?

Bet there are none :p

Mikey :cool:

I cant belive no one has said it .....your barking m8 :)

There said it :)

Andy

Cant believe no-one said:
The downpipe goes down and
the up-pipe goes..... I'll get me coat.

Dougie

£1000 missing out your wallet. (oh thats a disadvantage)

Mickey you still want more and more power.

Start with a ecu mod or a boost controller 1st.

I suppose thats the bug we all have,never happy and always want more.:D

Richard............

the downpipe is a big thing and the uppipe is a litter thing with a hole in it for a screw yoke.

That's the technical explanation though so I hope I haven't confused anyone :)

Gridlock:
Isn't the cat on the uppipe? That would mean there's a definite benefit to fitting one :)

Reading the description on the scoobysport website they say it was designed as a CAT replacement pipe for the 2001 WRX.

No cat on the up-pipe on Classic Scoobs AFAIK.

You're barking :p

(well you did ask us to ;))

On the MY01 there is a CAT on either the downpipe or uppipe. I had originally thought it was teh downpipe but that description on the scoobysport site would lead me to believe it is the Uppipe.

I'll check with the scoobysport guys and post back

I think you'll find it's both.
At least I think I think you'll find it's both :confused:

Does this mean that with the PPP and the Up and Down pipes I end up with no CATs at all????

Oh tits. That wasn't the plan. How big a job is the downpipe to remove and refit the cat if I need to do it? I'm told I only need the main cat to pass emmissions.

Get a beefy centre cat or "sports cat". Don't know what is sporty about a cat but there you go.

Sorehead

Yes, if you've got a PPP and you change out the uppipe and downpipe you'll have no cats. As John suggests, you could opt for a "sports" cat (really should be called a high flow or low loss, but I guess that the Marketing people think "sports" sounds better:rolleyes:).

Duncan ;)

Oh bum.
I've already bought the scoobysport ones. Oh well. I guess I'll just live with them until it's time for an emmissions test and then pay to have the old one refitted.

I'm a little bit annoyed now. Not with anyone else just with me. I thought the dp had the smaller cat and the main cat was somewhere closer to the back box. I thought that by fitting the PPP and dp I was getting rid of a cat either side of the main one.

So is the DP cat the main one?

WTF is "barking?" Break me down!

The main cat is the downpipe one. The third cat is not fitted to the JDM cars, but was added for Euro & North America spec cars. As for the uppipe cat - it is an aberation caused by the need to meet the fast warm up requirements. Only us "lucky" MY01+ cars get it - older models and the STi (which don't meet US regs) don't have them.

Duncan ;)

For the benefit of our visiting cousin - "barking" is a contraction of "barking mad" - normally used when somebody is saying something (or being completely) stupid. Perhaps apt for Mikey;):D:D:D

Even the cars without a cat in the up pipe will benefit from an after market one,as it is designed to flow better.(or so I am told)

hmmmm!

How little the majority of us know. Prime fodder for the 3rd party boys ;)

Mikey :cool:

WOOF !

I know I've seen Cossie Convert (now with some other screenname, though) mention that he gets 20 psi by 2600 RPM on his TD05 by modding several things, including his up-pipe. He seems to think the uppipe was an important part of this spool-up related mod, and his stock '95 RA uppipe was catless.

I think the obvious answer is that for big power (350+ bhp), you'll need to have a more free flowing uppipe, period. For those shooting for 300 bhp or less, who have stock catless uppipes, it is likely not a cost effective. This is even more true if you have a new age WRX with a cat in the uppipe.