welcome to subaru! they understeer....
more negative static front camber, and larger front sway/roll bar will help as well.
it appears you already have a good set of mods already. I would back off your rsb down some so its the same size or smaller than your front sway bar. TIC has a great article explaining why. trust me it helps.
also its a wrx and not an sti. the drivetrain (mainly differentials are not as sophisticated)
driving technique - i.e. weight transfer is really what your gonna have to change/get used to. your going to want to use momentum to get the rear out a little more right before you hit the apex to counteract the understeer, if that makes sense. ( you wont actually break the rear loose, just enough to get the weight transfer)
EDIT: personally, as i have run a very similar setup, assuming you are on 8k/6k standard bc coilovers, 16f 14r is pretty stiff. i would run something like 12f 8r on the damper settings (clicks from full soft). I found backing off the damping in an effort to allow a little more suspension travel will help outside tires grip better as weight transfer. this is just a suggestion based off nothing more than my butt dynos findings...ultimately i ended up getting tokico d specs and rce yellow and couldnt be happier. ****s all over bc coilovers that i used to think were great