Please use this link to an excellent site containing very comprehensive information about all Subaru models. The site includes all model years for every Subaru EVER sold in the US. It includes specifications, pricing, maintenance, warranty, safety, etc. A VERY good site to answer all of your questions about a particular year or model.
Thanks to amukaoen for the link!!!
Another great link which provides some good information on Japan, US and other spec Impreza platforms is here.
I use this a lot to refresh my memory on various models. It is a great resource for seeing the differences in model years, and between different country of origin specs.