boost pressure

i have been looking for an answer this evening and found some information that i hope will get me going in the right direction.... but i figure asking a few questions wouldnt hurt. on the highway at 2500 rpms im usually at around 4psi, when pushing abit harder the most ive seen is 11, i keep...

Truck starts fine, but when you take off going uphill from my house the truck will only go about 20 mph. No matter how much I press the accellerator it won't rev past 2000 rpm. Hissing noise from engine compartment. After a minute hissing stops and truck runs normal. Could this be the waste gate...

I have a 99 7.3 F-250. the truck has a 5" turbo back stright pipe exhaust, a pure diesel power 65 hp chip, and an intake. while driving the truck will build boost normally until it reaches 11-12psi then it seems like the wastegate opens and the boost pressure drops to around 5-6 psi. if i...