Scott @ SPO is definitely the guy to ask about this. He built his own one of a kind Legacy, awesome.
www.spomotorsports.com
From what Scott told me the US Legacy is wider than the Japanese spec car by about 1.5". I don't know if this is the track or the body.
Don't be suprised to find a car full of Clarion gear. If all goes well, the car will be SEMA.
George