A Quick explanation of ecu remapping or tuning

Software Re-calibration (also referred to as remapping or chip-tuning) is the easiest way to achieve power gains by customising your original ECU or TCU software.

The file is read from the ECU with specialty tools. This file is then modified with many parameters to yield the best performance and drivability. Some of the parameters modified are fueling, boost, timing, Torque limiters, speed limiters etc.