Got a great idea!
I came across this site that has blueprints for all kinds of cars, including Subarus. Its not like they're detailed blueprints, but its something. This is especially cool for people like me who do 3D work, because it has the basic perspectives(front, back, side, birdseye), so you can better visualize the car. You have to register to see, otherwise I'd post a direct link to the STi, but its easy enough to navigate once you've registered. They have many versions of the impreza, along with other Subarus. Just thougth I'd share.
Scratch Made Cars
http://smcars.nd4spdworld.com/