Rooked 930 and Miles,
I don't know about servo-valve wastegates, or if there are any such things. If there were, it might be interesting. But I have a light spring with and ECU-controlled solenoid valve. And for whatever reason, the system (ECU/turbo/wastgate/solenoid valve) can't be controlled to the level I'd like. I didn't study the Megasquirt system, but it looks similar to the DTA system, which is what I was using. Below is a screen print of the DTA window with my settings. Though it made a small difference in the correct direction, it didn't have nearly enough control range to reduce boost as much as I wanted. As I said earlier, it may have reduced engine torque by a few percent (up to 10%).