I fitted the 300mm ST 170 disc's and Mondeo Mk 3 calipers to my RS Turbo last weekend.I had ground the 4 ridges off the caliper and the top and bottom edges of the caliper carrier as in Glenn's topic from 2013.I then went to fit my S2 alloys and they did'nt fit over the brakes.From looking in I seen 2 problem area's.1st the top and bottom edge's of the carrier need more grinding.I had no electric in the shed,but I feel I can safely remove more without too much trouble.2nd place is a different matter!!! The back off the spoke's are hitting the outside edge of the carrier big time,and to me it looks like at least 5mm needs to be removed.This I feel would be unsafe and leave too little metal on the carrier.I could fit 3mm wheel spacers and remove about 2mm off the carriers,but this would result in it being a right pig to sit the wheel up on the little bit of hub sticking out,while at the same time trying to line up the wheel bolts with the hole in the hub.
Lastly,the spacer I needed to center the caliper on the disc was not 12mm,as reported widely on the web,I needed 15mm.
More grinding of calipers/carriers for me in the next week or 2.