downpipe or up-pipe?which to change
14 April 2004, 10:11 PM
#1
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downpipe or up-pipe?which to change
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
mark
14 April 2004, 10:41 PM
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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
Would doubt that either will help you too much for an MOT if the rest of the system is de-catted tho
Cheers,
Simon
14 April 2004, 11:08 PM
#3
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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
15 April 2004, 07:27 AM
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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
JIM
15 April 2004, 10:14 AM
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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.
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15 April 2004, 06:36 PM
#9
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
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
15 April 2004, 07:30 PM
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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.
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.
17 April 2004, 11:09 AM
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Originally Posted by Butty
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
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.........
17 April 2004, 07:59 PM
#17
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
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
17 April 2004, 08:40 PM
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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...
Incidentally Nick, the diagram you've posted above is for a normally aspirated Impreza...
Last edited by greasemonkey; 17 April 2004 at 08:42 PM.
17 April 2004, 09:05 PM
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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.
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