Yeah for sure, anyone can look at any new age STi piston and tell its cast. Version 8 JDM STi and USDM 2.5 STi both have similar casting marks. Version 7 were obviously forged.
Im sure they switched for a certain reason.
US STi piston:
1st pic is Ver 7 STi piston from APS website
2nd Picture is Ver 8 STi vs. ROSS forged piston.
3rd picture is of the underside of both... NOTE the similarities to the USDM STi piston with the JDM 2.0 ver 8 STi piston.
4th picture is of JDM ver 7 STi piston from APS.