Below you will find various electronic boost controllers mounted inside the cabin. They adjust the charging pressure via an electronic bleed valve that sits between the hose from the manifold to the turbo.
We have had very good success with installing 3 way valves in the way you see below:
Turbosmart E-Boost2. Electronic charge pressure control. Max 4.1 bar. With Turbosmart E-boost 2 you can control your charge pressure very precisely and adjust it via the clock.