SPD V2 Blow off valve 50mm black This blow off valve is delivered pressure tested to ensure the highest quality. SPD 50mm blow off valve is of the highest quality and can withstand very high high power applications. Thhis blow off valve has a very quick control and the piston is sealed with o-ring to ensure that it does not leak any air. Delilvered with banjo and vacuum connection for silicone hose. Adapter and fitting for pneumatic hose is also included. In order for the blow off valve to achieve its maximum speed of control, use a 1/4 "(6.3mm) vacuum hose. It is also very important that you use the right spring for your engine in order for the BOV to function optimally and not be open at idle. 1. Aluminum welding connection and V-clamp with o-ring seal so that it can not leak air at the V-clamp joint. The dump valve is installed with a 10psi spring upon delivery. Which is most common for turbo engines. But a spring set comes with springs of 8psi and 11psi. There are also springs of 2