Do GFB boost controllers use a ball and spring?

No. Some manufacturers use a ‘ball and spring’ arrangement in their manual boost controllers, with the claim that it brings the boost on faster by keeping the wastegate closed until the boost has nearly reached it’s peak level. This is a sound idea in theory, however it is worth noting that the "gated" ball-and-spring system offered by other manufacturers is incapable of holding back more than a paltry 2psi - certainly not enough to live up to the advertising claims.

Another nail in the coffin for the ball-and-srping design is poor boost stability. Since it is a dynamic system, and the ball can move slightly differently each time your engine comes on boost, the size and flow properties of the flow path through the restrictor and around the ball can change each time. This can lead to poor boost stability and random variations in peak boost level. The ball can even flap around like a pea in a referee's whistle whilst air is flowing through, resulting in a fluctuating output signal from the controller. Grab a boost gauge, a compressed air supply and a pressure regulator and see for yourself.

GFB boost controllers use a more consistent needle-valve bleed system, which brings brings boost on just as fast as any ball-and-spring system, and generally more quickly than a factory boost control system.