Factory detune and ECU tuning

Owners note the M156 is delivered in a relatively low state of tune in the C63 (commonly cited as 451 hp base, with the engine capable of far more in larger MB chassis), and that the factory ECU restricts throttle opening. A simple flash is described as restoring performance rather than abusing the engine, with tuned figures of 540 hp and above quoted, though many owners feel no need for one.