HKS Super SQV (Sequential Blow Off Valve) uses a unique sequential valve structure and a differential pressure control system, which allows for a broad operating range from low boost to high boost. Its Pull-Type relief design ensures stable operation regardless of the amount of boost pressure. The Super SQV will support new generations of turbocharged vehicles.HKS SQV4 super sequential blow off valve kit for the Evo 7/8/9 includes everything needed to install the BOV. Comes with a vehicle-specific pipe, new HKS couplers and install hardware. The SQV4 valve has one of the loudest and most recognizable sounds.