A manual boost controller by TB Developments. This is a reliable ball and spring boost controller.
The basic design of this ball and spring controller (grainer valve) is as the name describes. There is a ball that seats and seals inside the housing and is pushed upon by an adjustable pressure spring. When the boost pressure reaches the preset level the ball will lift allowing boost pressure the turbo actuator. The actuator will be seeing more than the 11psi +/- that it was designed for and will open the wastegate to lower the boost from the turbo. Once the Boost pressure has decreased to the preset level, 15psi for example the ball will reseat and seal. The wastegate will then close allowing the boost to rise once more until it reaches the 15psi again and the ball will lift. The controller will continue to do this keeping the boost at the level that it was set.
Also unlike the other form of Boost Controller, the "Bleed Valve" the grainer valve is a contained unit and will not allow the vacuum produced by the engine to escape. The grainer valve will only allow the actuator to see the pressure you what it to see. This operation is very much like the Electronic Boost controllers apart from that this operation is controlled electronically by sensors in their case instead of basic physics.
The ball and spring boost controller are very accurate and will allow you to reach the preset boost level first time, everytime. Without the worry of Turbo overspool or Boost spike.
Fittment is a very simple operation taking around 5 minutes in most cases
A full set of instructions and everything you need for this will be included.