I once seen a rally Scooby with something like this on, not this one before someone tell me lol and I don't know how it was done but sounded nice and different.
http://www.ultimatesubaru.org/forum/topic/71510-ideas-on-swaping-a-weber-carb-on-ea82%C2%B4s/
was nice and quick and no turbo. bet the turbo is a easier and cheaper fix though ;) .