Stock Class ?
 

Could someone tell me what class Impreza 2.5 RS's run in Solo II?

STX most likely. Maybe even DM - that's what my boyfriend's car was in (DM - RX Subaru) .. Go to your local SCCA club's website, look up the rule book, it'll give you the class, and what cars are allowed to be in there :)

Impreza 2.5RS runs GS. If you've done mods to put in in street prepared, then the Impreza runs DSP.

Check out this website if you have other questions about SoloII classes:

http://mouton.best.vwh.net/sccasolo/