Turbines actually aren't controlled by the pressure, the waste gate be it internal or external keeps them from surging and overboosting. These are primarily controlled by boost/vacuum etc. The turbine itself will continue to spool until it reaches max rotation and then it will actually reverse direction and explode. In sequential twin turbo systems a valve is used to control gasses whech feed a secondary turbine, "the 2nd larger one," while the primary turbbine, "smaller one," spools in lower rpm. When the engine hits said volumetric point, ie, "3500 would be full boost off primary," the exhaust route is opened to the secondary turbine opening up to a full twin turbo. Using a power plate to cut the gasses from the secondary/control them was the simplest and most readily available item I could find. At the same time I could trigger it mechanically with an external waste gate actuator I would run in to leakage problems as well as over all fabrication issues, "I don't have the capabilities for the green casting process." With that said I do appreciate your time as well as your insight. Do you have any ideas as to how to stop the motor at a certain point other than programing a chip?