If you are looking for 600 AWHP you will NEED the FMIC, and a nice rotated turbo, but that setup seems excessive for an auto-x car, IMHO. The price of the gearset sounds like an RA set, better than stuck, but no where near capable of holding 600 HP. Like state though, a hybrid build sounds right up your alley for your goal. Stay safe over there, waiting for my turn again also. Keep us posted on the build also. Good luck with it.
"2007 WRX- PPG'd, 20G- Tim Bailey tuned
Stage 2 2005 WRX