Ok, I have just phoned GSL Ralley Sports (very helpfull i might add) it seems S1 are a trick beast to match up. They suggest to actually measure my current disc & get back to them & they will try & sort something out. Prob is it will be too dark by the time i get home to get measurements (see from my first post) can anyone help me with some measurements or serial numbers as I need new rotors fairly urgently.....Cheers