From e-maps.co.uk:

When a manufacturer releases a car onto the market it has to be able to cope with many different demands in many different environments. For example, the car has to cope with poor fuel quality, poor servicing and at the same time provide reliability and economy. This means the manufactures have to make a compromise or “detune” your car. In the UK we generally do not have these issues to the extent that the engines have to be detuned so, we have the ability to change them releasing hidden power.
