If it was my car personally I would do the following:
Set of 18" rims
Cat back exhaust with quad tips
H.I.Ds
Coil overs
Slotted rotors
Upgraded pads
Change to the gt front bar (never liked the 3.0r front bar)
Front lip
Rear lip spoiler
Out back bonnet (bonnet bulges ftw)
Cai
Retune to get the most out of the zorst n cai n to get rid of that stupid throttle delay when u change gears quick

Just my two cents

thanx guys for your imput yeah im looking for some power gain and a little bit of cosmetic shoebaru thanks mate thats a big help i was thinking get the zorst done first i was looking at quad tips they look great with quads and then thinking bout some extractors and a maf tune then as time goes on get more serious im not looking for the fastest but im def looking to get some power out of it.

I know x-force make a cat back system but they have big twin tips, not sure about quads. Also u can look into a supercharger kit, there's a thread on here all about it.
Ultrex: http://WWW.ULTREX.COM.AU/ make lots of Subaru exterior bolt ons
If you look hard enough on some of these forums (subyclub. Ozfoz. Etc ) I'm sure u will find all u need