TiAL Sport is the leading manufacture in turbocharging components. Their durability, warranty, and performance stand no chance against the current market. Made in the USA The BOV comes either with an aluminum or steel flange. They also a stainless steel flange for an additional $30. The valves come in either a 7, 9, or 11psi spring. To help determine which spring you need, see this document provided by TiAL: TiAL Spring Pressure FAQ