you can also use cayenne, q7, touareg 6 pots on the front. The 17zr/l's work better because of the piston sizes and adapters are Ł70 from lee (cnc-machinist from r32oc/jack-the-lad-uk on ebay. just got mine from him and could not be happier, really helpful guy and very very good product. work with r32 discs or 350x32 ecs'. My calipers are off for painting but will get pics when ive got them back.
And if you are after different adapters im sure lee would be up for a challange and cheaper than most