ok, well first off (not to go off on you, this to everyone) i'm sick of everyone basing a turbo on how much boost they want to run. its going to be completely differerernt for each turbo, for turbo is going to flow more then another turbo, you can base a power goal around psi, you have to base it off a power goal, but if your only looking for 250, you'll have no problem making them, if i was you i would shot for a little more but thats me. 300 is about the safe limit on stock internals, but when would you like to hit full boost is another thing to think about.