Well, I would say that the most cost effective option, IMO, would be to find an SVT OEM Cat and that would be good enough to do OK at local events in STS.
You could add a LSD and increase wheel/tire size and run in STX.
I don't know if the SVT focus will ever be competitive in DSP...
You could go back to stock and run HS though I don't know if that's in 2009 or 2010
Parking Lot Hero
2008 WRX daily driver
2003 ZX3 23D Autox Car 42 FSP
"Hella Functional - Raced, Not Hard Parked"