Rimmer is not the only Supercharger desinged for Subaru's.. There is Force One. I don't have the link with me at work, but I will provide it later tonight. They have a kit developed for the MY00-> 2.5L legacy engine (same as ours basically). It is a side winder kit and looks very nice. I found the info here on the I-club so do a search on "Force One superchargers" and you should find info if you can't wait for my post tonight.
Thanks - Jon