If the struts are original, you'll need to replace them; they are a wear item. The same goes for your tophats.Originally Posted by 508 STI
Properly matching dampers and springs (whether struts/springs or coilovers) will avoid having a crappy ride quality.
Often times, struts/springs are recommended as they are less maintenance than coilovers, and in the past, the price point you can get a decent strut/spring setup has made it impossible to have a coilover even close. The gap has been reduced with the introduction of both ST and HVT coilovers for the GD Impreza. If you want to go strut/spring, Swift Sport springs with KYB GR2 (basically, OE-replacement) struts is your best bet. Upping your budget a little, you can get into coilovers.