Why not an external wastegate?
No need. The additional complexity and expense is simply not required on these applications. We are able to achieve stable, consistent boost levels on these units with their internal actuator wastegates. Different boost levels are available through the different actuators we offer. And they all work wonderfully with boost controllers, electronic (preferred) or manual. Other turbo makes MUST use external wastegates, either because they do not exist with effective internal wastegates or due to improper sizing.
