john coffey

I have heard mixed reports that they are a lot of work to fit for not a lot of gain, is this true?
Apparently the real gains are to be had with the 2001 WRX model, can anyone confirm?
Cheers

Fatman

That modification isn't recommended for an MY00. The reason is that the after-market up-pipe is intended to replace a section that normally has a catalytic convertor in it (with a straight-through pipe). The MY00 has no such up-pipe cat, so there's no particular restriction to remove.

A comment from jonny gav in this thread suggested there's alternative benefits to be had from porting the existing up-pipe, for very similar money.

sparkster

John,

Changing the up-pipe for a 2001 wrx and after will mean decatting that particlar section of pipe hence the decent gains for earlier models.

The older models, pre 2001, dont have cats in the up-pipes and therefore the gains are not that significant.

However, for these older models there are benefits in replacing the up-pipe. A Scoobysport up-pipe for example will be slightly larger than the original and match the intake port to the turbo. I'm led to believe that it is generally a "cleaner" pipe.

This better gas flow helps to reduce cyclinder temps and aids turbo spool up giving better throttle response.

I'm in the process of getting this fitted for my 93 wrx but am more interested in the reduced cylinder temp side of things to reduce the likelihood of detonation.

If you could afford it, a good thing to get done at the same time would be to get the headers ported.

Yes it is a tricky job. Supposidly three hours or so.

Mark

Fatman

...good points. In addition to dropping cylinder temperatures, there is some flow benefit (don't ask me to quantify - I can't), and is still a recommended mod if you have to have the best available.

john coffey

Thanks for the info, interesting stuff.