could just fit an sti5/6 one, good for 330 bhp, get them gor 100 quid.
I wouldnt buy an after market top mount, as Daza said spent the money on Fmic.. could also go STI8 tmic, but a bit of work in it and will probably cost near a fmic again its done, you will defo need map for fmic and maybe sti8. Sti5/6 shouldnt be a problem.
Think i have a standard wrx one, should be in good nick, 30 quid if you want a cheap and cheerful fix