Billet Rack Cap (also sometimes called the rack plug), made of the highest quality Billet Aluminum, allows full rack travel of the Bosch P7100 injection pump. The Attitude Rack Cap is drilled to 17mm, which is 4mm deeper than a stock rack cap. This allows for full 21mm of possible rack travel which provides more fuel flow, equating to 20+ more HP. Fits on all Bosch P7100 pumps