Weight and cost are higher. Greg is using a intake manifold pop off valve.
The down side of this is higher intake air temperatures as the
compressor is working hard all the time up to and including
when the pop off valve opens. It is a good idea to keep the intake
air temperature down so the engine is less likely to detonate.

With a waste gate this is not the case. The boost is limited by
the turbine.

A built in waste gate is one of the attractions of the stock 89-91
turbo's.

Paul Lamar

All good points  except, what are the compromises that are being made? I think we need graphs and charts comparing the various options as to how this effects performance in climb and cruise. 
...Chrissi

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