both.

10psi is ok on a T3 or T25
10psi is NOT OK on a GT4088R

whp just helps guess what the motor is making relative to turbo size. if you tell me your making 250whp at 5psi, then i assume you have a monster turbo. bevcause thats the only way a D series makes that kind of power, with a big turbo.

you say your making 250whp at 10 psi, then i assume its a T3/T4ish setup.

either way, Boost relative to hp output is what kills a motor. A d series we dont reccomend past 10psi or 230-250whp on stock motor