I believe they run 11psi stock. A stock supra turbo has one bov. It doesn't vent to atmosphere, so it is hard to hear. The boost pattern varies some from car to car, but in general it is close to 8-6-11 stock. I run my car at 15-16psi daily, and many go higher than that. Of course it is harder on the motor, but I wouldn't worry about it hurting the engine unless you run lean. So, pay attention to your spark plugs. I would definitely keep it under 18psi on pump gas. With race gas (100+ octane) the stock turbos are too small to produce enough boost. You actually risk destruction of the second turbo more than the engine at a higher boost. Hope that helps. Oh, and no boost gauge.
Daniel