here is another reply from a tuning company:
"Hello,

Thanks for your enquiry.
To the untrained eye the vehicle will appear to be totally standard and BMW's diagnostic systems will not report any difference to the vehicles ECU, however, a good technician well versed in the way a particular vehicle works will be able to analyse the injection duration and a few other parameters to deduce that the system is indeed running different to original specifications. That said, these vehicles are so much better after a remap that its plainly obvious it's been remapped anyway as the difference in performance is night and day."


Not sure how the injection duration is measured?through the obd once again?