I was told by my mechanic to keep turbo below 28 psi, said these trucks do not like that much pressure. Today I passed two 18 wheelers on a 1 mile 5° grade at 2800 rpm and 21psi on turbo with my 2006 F350. Doing 55 mph. Take it easy and she will treat you fine.
Let me edit a little on take it easy, as others have said don't baby it. They like to be driven hard but overboosting you'd turbo is not good for your truck. I drive every Saturday when not towing and once warmed up take the turbo to 25-28 psi to keep the vanes moving freely. Have not had any turbo issues since doing this.