rally design do them as a kit, 283mm discs, wilwood 4 pot calipers and mounting brackets for around £450, then u need to add pads at £50 and braided hoses at £30 if u dont already have them, u can just buy the calipers and mounting brackets but it only works out fractionally cheaper than buying the kit, dont go for the dynalite calipers (i had these) they flex a bit and have no anti rattle springs/clips and no dust seals, best ones to go for are the midilite calipers as these come with dust seals and anti rattle clips and flex less

they will fit a s2 on std rims fine, if its a s1 then if the anti roll bar is not perfectly aligned then they could catch it (this is what rally design told me)