RY17040-BV Riva Yamaha SVHO/SHO Performance Blow-Off Valve Kit The Riva Performance Blow-off Valve Kit improves supercharger reliability and performance by relieving unwanted pressure during off-throttle operation. Reduces supercharger clutch & gear wear and eliminates heat soak in discharge tube. High-strength silicone hose with integrated HKS valve installs easily in place of OEM elbow joint. Includes high quality HKS Super SQV (Super Sequential Blow-off Valve) that features unique sequential valve structure and a differential pressure control system, allowing for a broad operation boost range. Also includes vacuum line and fittings necessary for installation on SVHO & SHO engines. A simple and cost effective upgrade for both stock and modified engines.