Agree with most of what claude has said, on the maps shown it would be better if the turbo rpm was shown, you know approx how much air the engine must consume 1 pound of air = approx 10bhp, so 400 bhp devided by 10 =40ppm
look at the comp map for the required airflow, and best or at least still good efficiency part of the island on comp map, and the pressure ratio checked against boost pressure, then at the speed the turbo is running at to create the required airflow,
Regards Dave R.