Four year old thread and full of bad information,I am afraid.
How you remap a car depends on what ECU it has and what equipment you have to carry out the procedure.
Just to give an example,four years ago,all BMW cars with EDC16 ecus,had to be done via BDM(direct to Ecu) and only recently has it been possible to do via OBD but the equipment to do this is still very expensive and takes a long time(+30 mins),so quite a lot of "tuners" still do it via BDM.
We have also been dealers dor Superchips Uk for a number of years and only for the last 2-3 years have we been able to map Edc16 Bmws via Obd with our Vspire equipment.