In 2003, John Cooper Works released the first tuning kit for the R53 MINI Cooper S. It was strictly a dealer-installed accessory and included a JCW cylinder head, exhaust system, engine calibration, supercharger, and badges.
This eight-page brochure from the UK and printed in March 2003 gives some background information on John and Mike Cooper, describes the parts of the tuning kit, and displays the performance gains.
Download the John Cooper Works Tuning MINI Cooper S brochure.