Wastegate psi ? Does anyone know at what psi the turbo waste gate should start to open?

Usually they come preset at 8 or 10psi. 10 would probably as high as you would want to go at your elevation without engine modifications. I'm running 12psi but I'm usually at 5000' elevation. To increase the boost, shorten the actuating rod.
By the way, I just bought a full set of Big Horns to use in Moab. Once again I'm taking your advice on tires

Mine was originally putting out almost 10psi until I installed the intercooler bringing the boost down to around 5 or 6. I would still like to keep the cooler. If I shorten the rod to the wastegate that should increase boost? Any idea how many turns will it take? I promise you the Bighohrns will out do all. Good for you.

Actually, I may have given you some bogus info. If the waste gate actuator rod pulls, lengthen it to increase boost. If it pushes, shorten it. Try 1/4" and fine tune from there.
When I installed my intercooler, boost dropped about 3psi which makes sense. As the hot air cools going through the intercooler it becomes more dense reducing the psi. Also, try tightening your intercooler tubing clamps. I was loosing about 2psi from air leaking past my silicone unions that I thought were clamped tight enough.