Features: 1.The BOV is a pressure relief device on the intake tract to prevent the turbo's compressor from going into surge. 2.The valve can use a combination of manifold pressure signal and spring force to detect when the throttle is closed. 3.When the throttle is closed rapidly, the BOV vents boost in the intake tract to atmosphere to relieve the pressure and eliminate surge. 4.With 8 discharge ports that draw in surrounding air and release an aggressive JDM racing discharge sound. 5.The turbo BOV has dual spring system to promote response and hold up to 30 PSI boost pressure. 6.The blow off valve is with 2 bolt mounting design and 40mm hard?anodized valve for increased airflow. Specification: Item Type: Blow Off Valve_x000D_ Material: Aluminium_x000D_ _x000D_ OEM: SDD-BOVGRSBL, FPG250_x000D_ Size of Flange Pipe: Approx. 2.5in/6.4cm_x000D_ Application:_x000D_ For TYPE-S Dump Pipe Flange_x000D_ For TYPE-RS Dump Pipe Flange_x000D_ _x000D_ _x000D_ _x000D_ When the throttle is closed rapidly, the airflow is quickly reduced, causing flow instability and pressure fluctuations.Surge can eventually lead to thrust bearing failure due to the high loads associated with it._x000D_ The valve can use a combination of manifold pressure signal and spring force to detect when the throttle is closed._x000D_ _x000D_ When the throttle is closed rapidly, the BOV vents boost in the intake tract to atmosphere to relieve the pressure and eliminate surge. PackageList: 1 x Turbine Valve 1 x Hose 1 x Flange Pipe 1 x Flange Pipe Interface 1 x Gasket 4 x Clamp 2 x Nut 2 x Screw 2 x Bracket Note: 1. Please double check the part number of your item, matching information is for reference only._x000D_ 2. If you are unsure of the item, please contact us before buying to avoid unnecessary return, thanks!