What type of driving do you do? City, highway, mountains, autocross, track
events, drag racing? Pad compositions run from soft (quiet, good at low temps,
fading at higher temps) to hard (noisy when cold, higher pedal effort/poor
stopping when cold, no fade in racing/mountain usage).
In my Miata, used for a few track events a year and frequent commuting, I've
used Porterfield R4-S. They're fairly expensive and dusty, but don't squeal,
are decent when cold and give fade-free confidence at the track. Not sure if
they'd be right for a WRX. Brands I've heard recommended include Axxis and
Hawk.
Try looking around at these sites:
http://www.wrxforum.com/cgi-bin/ultimatebb.cgi
http://www.imprezawrxsti.com/postnuke/
http://www.cobbtuning.com/
http://www.spdusa.com/
http://www.subarureview.com/
http://home.att.net/~teaguesauto/
http://www.vishnu-performance.com/
...Rich S.