I run a GT4202R low pressure turbo with a .040" restrictor (30 psi @ the big charger with truck cold oil at 80 psi), oil supply is teed off of the factory charger supply. Note: this turbo is water cooled as well.
I pulled the wife's Trailblazer SS down from Fairbanks to Seattle to Salmon Id. to Rexburg, with Lots of extra fuel, spare tires, 10,000# trailer, & enough tools to rebuild anything on the side of the road. I'm guessing 10-11K ish. 40-75* temperatures, Rotella Syn. 5-40, 40psi oil pressure cruising 5th gear, 15# boost, Egt. 700-900*, water temp 210*. My oil pressure has never dropped below 40#, pulled lost trail pass at 55 22# boost 1050* egg's. Truck has 72,000 miles.
Not sure if any of that is useful or not... I just noticed I run thinner oil than most for the cold climate Im in but still hold the same oil pressure. Maybe the water cooled low oil pressure ball bearing turbo is helping, maybe not? I need to install a oil temp gauge now to satisfy my own curiosity.