You do not understand the difference between flow, and mass flow.
If you were to hook up your manifold to a pressure regulator with unlimited flow, your Hp would be directly proportional to pressure. This is all i am saying.
All of your turbo statements have a lot more involved than just pressure. Obviously bigger turbos make more power.
other variables you are not accounting for.
-heat
-the area under pressure vs flow graph
-back pressure
-turbine acceleration
-compressor maps
-turbine efficiency
-windage losses
It is the combination of those 7 things and more that make your engine perform better than a K03 car.