HKS SSQV Blow Off Valve Kit - Subaru WRX /STi 02-Up. The Super Sequential Blow-Off Valve (SSQV) is a pull type relief valve. The SSQV is actuated by pressure alterations only, ensuring quick valve response and complete closure during idle. Typical blow-off valves utilize large valves in order to accommodate high boost/high hp applications. However, these large valves react slowly and require high activation pressure to open. Smaller, fast reacting valves, do not permit the air flow required for high horsepower. The SSQV incorporates both for maximum performance. It is engineered utilizing a small primary valve and a secondary valve for additional relief capacity. The SSQV is made of billet aluminum and emits a unique aggressive sound.