Based from what i've heard/read, lightweight pulleys are more acceptable than under drive pulleys. couldn't remember the specific reasons.

JaDaM wrote:

What i understand is the crank pulley is larger so therefore providing less drive to whatever is strapped onto it. i.e. less drive to the power steering, alternator etc. reducing leaching from the crank will should increase HP but also heard this can be a problem cause less drive to the alternator means the battery isnt charging properly and can damage the battery and the power steering and air-con arent as strong which can be less comfortable in daily driving. Anyone experience this or is my reasearch correct?

Zerosports market some designed for our cars and those supposably give you some gains. It may be possible to get the impreza ones to fit which may be easier to source (on the zerosports website, it says their WRC Crank Pulley suits all EJ engines). Might be worth checking out the wrx forums for their experiences. Let us know if you do choose to go with one and your experience with it.

http://www.zerosports.co.jp/shop/Pmain_ … index.html

Also found this thread, which if you read through it, suggests they are fine.

http://forums.nasioc.com/forums/showthread.php?t=437237