If Subaru can get 250hp out of a 2.5L boxer 4, then I would think that Mazda could get 240hp out of a 2.3L I4.
The MZ3S gets 160hp out of that 2.3, and only an additional 40hp gain from a turbo would seem weak to me.
Edit: The non-turboed Subaru 2.5L H4 gets around 160hp as well.