100 and 115 1.8 TDCi of Focus mk1 difference was only ECU map. 115 version was introduced first and after some months 100 version. I do not believe Ford bother to work on new pistons, cylinder head, cams etc. The only thing perhaps: turbo? (but it was in general Garret 1749V having only some different series numbers), then even more: injectors and CommonRail Delphi parts are also the same. As real program modification of ECU shows the same results: both 100 and 115 are able to go to limit of 140, I state as above: there are no mechanical differences between them. If I am wrong, please correct. Thanks.