thanks guys,so what i have found out is
front,brembo calipers from a blob,hawk or hatch will fit straight on to the wrx you ideally want the bolts as well but can order them if not supplied with calipers,when ordering disks you need to order 2004 sti disk,also need to change the brake lines as well and your good to go up front.
rear is more a problem,brembo calipers from a blob,hawk are not a straight fit you need to find somewhere that sells an adapter braket for them to fit or have someone make you one.calipers from a hatch sti are a straight fit,just need to trim dust cover to fit disks you need to have them redrilled with 5-100pcd or find some muliti fit pcd one's but i have not had a look to see what brands makes do them yet
so is it worth messing about with rears or just have brembo fronts and crap calipers rear,or big brake conversion front like k-sports or something up front and crap calipers rear,personally i would like nice brakes that are the same all round so think the big brake k-sport thing is not for me as it would bug me every time i look at the crap rear calipers,so i think in the end i will go with the brembos all round when they come up from a hatch sti.