A pedal box changes the throttle response of your car and has a number of different settings which allow you to tailor it to your liking. As the throttle is controlled via wire, the box interupts the signal and changes it to make the car respond to less input. In practice it means putting you foot down less for the same amount of acceleration, but that doesn't do it justice. Although it adds no power to the car, it makes the driving expirence much more enjoyable, and does away with the dead area at the start of the peadal's travel. DTUK's version is the most popular and are around £200. They are also very simple to install.
