I'm new to the Subaru world, but I thought there was a difference between the legacy and wrx wheels. legacy = 5 x 100, wrx = 5x124, or something like that. Am I mistaken?
Just so I'm clear: standard wrx wheels have the same bolt pattern as the LGT. It's only the 2005 + STI that has a different pattern? That could make my life easier ....
You should look for some 17" rims. The only reasonably prices 16" rims that might (I am not sure) are 98-01 Impreza RS wheels, and those will probably cost more than OEM 17" takeoffs and be in worse shape. Search legacygt.com for a definite answer on RS rims. If they clear your brakes - try to get them, they will allow narrower tires, which is better for winter.