From what I've heard the STi version will mostly be cosmetic.
Most of the shops and vendors I know are getting their FR-S ready for SEMA. It's so crazy right now a lot of shops aren't even taking customers so that they can work on their SEMA cars.
At there moment the forced induction options are very poor for the car. HKS has their supercharger, GReddy has a turbo kit. But for street applications I'm hearing 4-5 psi of boost.
The FR-S drift car from what I heard is on it's 4th motor.
From everyone who has worked on the car 1) it handles great 2) slow as shit
Was visiting my friends the other day. Roll cage was being welded in as well as hydraulic jacks.
After SEMA there will b a lot more options but until then buy one and work on suspension, tires and wheels. I do know there are some FR-S in Japan doing 300 rwhp though.