Sometimes a car cannot be remapped through the OBDII port in the vehicle. On these occasions the ecu needs to be located and taken apart so that I can connect to it directly and program it that way. The ecu in the Nissan Xtrail is an example of this.
Reading the full information via this method can also be useful for ecu repair work but for the NIssan today it was just more torque, more power and more economy. Power increeased from 136 to over 160 bhp.