I was heavily into autox with the Philly region for ~4 seasons. I have not been out since 2010.
Have a look at my mod list. I started out in STX, then SM with a mild turbo upgrade and 21 psi of boost.
I think I hit an ability plateau - the WRX has become far more capable than I am as a driver. Going out to an event became an exercise in frustration. Might have been more fun if I had stayed in STX. I get eaten alive in SM.
Did a track day last fall. That was the most fun I've ever had with the WRX. Way more seat time and I think a far better better value per dollar / smile wise. Is is much harder on the car though.
Not sure what I'll be doing in 2013 ...