Why would ou even compare a Nissan straight 6 to an H4 motor.
Anyone with half a brain, and could spend a little time reading actual facts before spitting dribble would know Subaru only went down the 2.5 route to meet emission standards in international markets.
While incresased displacement does have its advantages, the 2.5 is still just a supporting act to the EJ20t.
And you can harp on about potential all day, but unless you are talking power figures well north of 300kw@wheels, your arguement stands on shakey ground.