The letter to "Phil" from McLaren managing director Antony Sheriff details the changes as an 18kW power increase for the 3.8-litre twin-turbo V8 seeing power reach a Porsche 911 GT2 RS-rivaling 460kW, improved throttle response through re-mapping the engine control unit (ECU), remote-opening passenger door, programmable engine note and audio system enhancements. All free of charge and all without effecting the McLaren's existing emissions and fuel consumption figures.
McLaren's Wayne Bruce confirmed the authenticity of the letter to CarAdvice and the availability of the upgrade package, which also includes an update of McLaren's IRIS navigation system.
The changes will be available worldwide from October through individual dealers, so if you own one and still crave more power, contact your local dealer for more information.
Click here to read CarAdvice's McLaren MP4-12C review.