We need to know VE, and I am almost sure that most tuners if not all don't know the actual VE numbers for this motor.
The motor by design should have a VE of higher than 90% though. Until we know VE, everything about HP, turbo choke, etc. is just speculation.
Efficiency alone will dictate how much power at a relative amount of boost pressure. A highly effecient system can make 400 HP at 10 PSI, while a more parasitic system could produce 370 HP at 14 PSI on the same turbo's. (these are just arbitrary numbers by the way, not actual numbers)