So I was reading the forums for a couple of weeks about people doing the 312mm disc upgrade with S3 TT etc calipers and carriers. I picked up some calipers and carriers that had just been refurbished with new seals etc. The only thing now is I put a caliper side by side next to the orginal caliper and they both look exactly the same size?? Why is that? Is it the inside of the S3 caliper is deeper that allows you to fit the 312mm disc? These are the ones I bought...