Suspension

From The Wiki

the 2008 WRX has a 20mm front sway bar and a 15mm rear sway bar

the 2009 WRX has a 21mm front, w/ a 16mm rear

the 2008/9 STi has a 21mm front, w/ a 18mm rear

the rear STi sway bar WILL fit the WRX, the front STi way bar will NOT fit the WRX

the 09 WRX received firmer springs- to the tune of 40+% stiffer, along w/ the firmer springs- firmer valved dampers

the 09 WRX also received firmer tops front & rear- these are the same tops as the STi uses (same part #'s)

the STi utilizes springs that are the same rate as the 09 WRX, but uses different dampers- the STi front dampers will NOT fit a WRX, the rears would but no real benefit to the STi ones over the 09 WRX ones

to the part #'s

09 WRX front sway bar (21mm) 20401AG040

09 WRX front sway bar bushings (need 2) 20414AG070

08 STi rear sway bar (18mm) 20451FG010

08 STi rear sway bushings (need 2) 20464FG010

09 WRX front right strut 20310FG080

09 WRX front left strut 20310FG090

09 WRX rear shock (need 2) 20365FG060

09 WRX/STi front top 20320FG010

09 WRX/STi rear top 20370FG010

09 WRX springs front (need 2) 20330FF060

09 WRX springs rear (need 2) 20380FG090