You need a P18-style flange I think. A VF29 etc. is similar. The VF28 came stock on v6 EJ20x motors (2.0L). I'm betting a vendor on the site list will have a flange for that. I don't know where you can find a graph though.
EDIT: To clarify, the v6 was an Impreza from 2 to 3 versions ago and not directly imported into the US in 2.0L turbo form.
EDIT2: This turbo should be good for 300+ HP and with proper fueling could yield as much as 350 HP or so on a Subaru EJ207 motor, which is an earlier WRX STi version.