Stock 400 Piston Boost

@j par The wastegates are controlled exhaust leaks. Spring loaded valves with a value (X) in pounds for the spring. Anytime boost>X the valve opens and “wastes” exhaust energy, therefore no longer driving the turbine and slowing down the compressor, limiting boost to that level. A blow off valve works similarly in that it blows off excess pressure in the charge side when the throttles are slammed shut and the turbo is still spinning thousands of RPM.