on a MY01 that so far has a straight thro exhaust from downpipe onwards-baring in mind that a middle section cat is easy to put back on if needs be for MOT-if u could change only the up-pipe or downpipe which i sbest considering MOT- plus for power effect-plus i dont want any shortening of engine by any mods i do-any help please

mark

 

I would be inclined to do the downpipe first, but as it'll have to come off again to do the up-pipe, do both

Would doubt that either will help you too much for an MOT if the rest of the system is de-catted tho

Cheers,
Simon

 

but if u was only going to do one or other which is best? i can then re -add centre cat on at MOT time making 2 cats so thi swill pass

 

If you do only the downpipe there is a small possibility (due to extra flow) your up pipe cat and EGT sensor to break and destroy your turbo so better do both up-down pipes.
JIM

 

If you really only want to do one of them I'd be inclined to do the downpipe, although there a couple of theoretical issues as mentioned by Jim above.

 

If you can stretch to both then do them both.

Come MOT time just make sure the engine is nice and hot and the centre cat should do enough to make it pass.

Nathan..

 

how easy is it to change the down pipe urself-i do have tools and ramps so is it a job u could do urself?

 

Is there a cat on an up pipe on a MY94

 

To add to this I might just add that my MY04 doesn't have a cat in the up-pipe - there's one in the downpipe and one in the centre section(s).
I presume that the MY03 is the same as this.
Isn't it only the MY01/MY02 that has a cat in the up-pipe and its removal is where the MY03/MY04 gets some of its extra power.
Nick

 

nick, yours does have an up-pipe cat if its the same as the MY03 m8

my94 would probs have an up-pipe cat, although the gains on the classic aren't as significant as on the bugeye / blobeye.

mark, give the bolts / studs on the back of the turbo (do it when cold!) a good spray with WD40 type stuff, and leave to soak. You should be able to do the job yourself, the major part of the job is getting rid of all the stupid heatshields.

cut the heatshields to re-fit them as they prob won't go over your new d/p.

when you choose a downpipe, for max gain make sure you buy an open neck or twin dump. some blank off the wastegate side, which isn't what you really want.

 

Oh dear!!
I'm going by my CD manual which only shows one exhaust system for the WRX and STi.
There's deffo no up-pipe cat shown so is this the STi system I'm looking at?


Nick

 

Probably the USA version of the manual.........

 

I will check IWOC as I'd be interested to know- unless anyone on here knows if the US version has an up-pipe cat?

 

MY01 has Uppipe cat-MY94 doesnt-MY03 from what i can recall was the changeover year for the uppipe cat removal.

 

my03 has up-pipe cat

 

Here's a pic. Its called a Precatalytic converter part 24 below

 

I wish I hadn't started this now.
Yes - CD is for US cars as it details the STi as being 2.5 litres.
There is only one piccie for the exhaust on the CD for all cars, but looking at NASIOC, the WRX owners mention that they have the pre cat in 2003 cars.


And then I see this for an STi UK up-pipe for sale as having no CAT?
http://bbs.scoobynet.co.uk/showthread.php?t=319196
I presume that both US and UK WRX have a precat while all STis don't?

Nick

 

The exploded diagram published by PeterUK300 above is from the MY01 workshop manual. To the best of my current knowledge the MY03 and onwards UK specification WRX's don't have a catalyst in the up-pipe.

Incidentally Nick, the diagram you've posted above is for a normally aspirated Impreza...

 

Excellent news GM..
I wonder what other fun this CD is going to get me in, still what do you expect as a cheapy off Ebay.

Nick

 

I'd imagine the vast bulk of this sh*t that floats around ebay will be from the USA. Can cause problems just like this when folk start assuming the cars are identical across the world.

 

anymore views

 

greasemonkey, you have a PM m8

 

So.............. does the UK MY03> have a precat or not???

Nick

 

yes