My boss has an 03 (I think) Forester with the XT 2.5 in it, with a 4AT.Cascade Outback said:
The turbo lag is PAINFUL for city driving. The engine's great above ~3k, but before then, the car can't get out of its own way. It really turned me off to the factory turbo setup, as I do far too much city driving. Perhaps with a slightly smaller aftermarket turbo that would spool quicker, it may be different story.
An H6 (which was an option on the OBs, so another "should be fairly simple swap for those so inclined") looks like a better idea to me, but then again, I like the broad, fat torque bands.
Let us know how it goes! If you can deal with the lag in the setup, I think you'll be impressed. After 3k, my boss' car seems to really speak with some authority. I think it could be fun as a track car, just not as a daily for me.