The phrase "active valve" refers to a type of valve that can be controlled and adjusted electronically or mechanically. It is used to regulate the flow of gases, liquids, or other substances in a more precise and efficient manner. Full definition
The new model features a host of improvements including new advanced technology like the 12 - inch digital cluster and available active valve performance exhaust system. (tprm.com)
Quiet Start comes as part of the optional active valve performance exhaust system. (evo.co.uk)
The WRX STI's revised 2.5 - liter intercooled turbocharged Boxer engine, now with Dual Active Valve Control System (Dual AVCS), produces 305 horsepower (SAE) at 6,000 rpm, a gain of 12 over the previous model. (thetorquereport.com)