Your next mod has to be camber plates, this made a huge difference with my car, back when I was in ST, and they are now on my FSP car. I also highly recommend V710s, I got around 20 events on a set (1.5 years worth of events).
Check the rules on the rear control arms, I believe you're allowed to make one change to adjust camber.
Parking Lot Hero
2008 WRX daily driver
2003 ZX3 23D Autox Car 42 FSP
"Hella Functional - Raced, Not Hard Parked"