There is already a FA20 DIT in production, which makes 300PS (~296hp)
[ame="http://ja.wikipedia.org/wiki/%E3%82%B9%E3%83%90%E3%83%AB%E3%83%BBFA%E5%9E%8B%E3 %82%A8%E3%83%B3%E3%82%B8%E3%83%B3"]スバル・FA型エンジン - Wikipedia[/ame]
http://www.subaru.jp/legacy/touringw....0-gt-dit.html
So 240PS from the 1.6L version seems about right.