chances are the boost pressure is actually absolute boost pressure ie 1.5 bar - 1 bar = .5 bar which is around 8 psi which makes sense. Its highly unlikely that they will release a car with 10:1 CR and run 18 or 22 psi.
. If you log parameters in any of the turbo powered DMEs you will see they actually measure absolute pressure and derive boost pressure from there. the reason is to account for altitude.
Harry