The loss in boost is minimal, only 1/2 - 1 pound of peak boost which the majority of drivers could cars less about.
This guy does not have a clue of the term "Volumetric Efficiency"
How did he determined the loss???
From the gauge??? The are variations on the OEM boost gauge and the loss will be increased based on other modifications to the engine like exhaust.
This buyer beware information should be relayed to the other Grand Prix and Buick GS sites and clubs.