Shop wise if you called them pretty sure they could advise on bits that would fit, induction kits, exhaust back boxes, wheels, strut braces, suspension parts etc would more than likey be the same as a WRX.
http://www.just-subaru.com
http://www.scoobyworld.co.uk
http://www.japperformanceparts.co.uk
http://asperformance.com