i use a full st24 setup on my mk4, discs, pads, caliper and carriers so yes they do fit. you need to drill the hub bolt holes out 1 or 2mm for the bolts to fit though and get some spacers made up from stainless steel so the carrier sits central over the discs or if your feeling cheap large ewashers will do just as good a job as spacers.
so all in all st24 discs DO FIT