Something else you are missing is the size of the turbo.
My FoST for example flows upwards of 23psi but at 2700rpm and that is where it makes alot of Torque, but run that turbo out to 6500rpm and it is only flowing 14psi.
Change the turbo on the FoST to a bigger turbo like the GTX2867R and at 23PSI near redline is it…