The BRZ S is a stock standard BRZ with STi parts installed by Subaru Australia. I can confirm there are no modifications on the engine. Subaru Australia has called it the BRZ S rather than the BRZ STi for this reason.
More information -
Subaru BRZ S
Went to get my car service last week, here are some photos of the BRZ S at Subaru Docklands (Melbourne)
Bonus - 2014 WRX Concept
