I'd get these:
STI ADJUSTABLE STRUT/SPRING SUSPENSION KIT*
Inverted strut and spring design with variable height adjustment. Includes a 4-position strut damping adjustment on front and rear struts. Strut diameter is increased from 22mm to 39mm on 2.5RS and WRX (equal diameter on the STi model). Springs initially lower body approximately 10mm on 2.5RS and WRX, 20mm on STi model, and may be adjusted an additional 30mm.* http://www.subaruofamerica.com/microsites/spt/main.jsp
They usually run 30% off every other month, so not a bad deal for $1700.