Worx's EVO valve offers lightning fast response with the precision of a surgical instrument, and some of the finest CNC Machine work you will ever see. The patent pending valve design offers the proper air return needed by air flow metered vehicles, but also features a controlled atmosphere vent which can be run closed, or in four stages of vent. Additionally, the staged design makes the rate of atmosphere vent variable depending on boost pressure at time of release. The Worx DualStage valve offers performance valve benefits, without sacrificing daily drivability