gauges (boost problems)

[Scuba623]

So i installed gauges today, egt, boost, trannie temp. The question i have is that the boost gauge only reads when i accelerate with more than 3/4 throttle and then it only goes up to 12 psi. Is this right?? I jumped the boost gauge line onto the map sensor line but i have heard that you have to have it on the intake manifold? Not too sure what is the best...what about tapping into the top of the turbo housing? I also towed my flatbed today with maybe 3000 lbs on it and when cruizing at 60 mph i get no reading from the boost gauge at all unless i accelerate to change lanes or something. I am new to these gauges so not too sure what kind of readings i should be getting. Also, what is a safe trannie temp to run at? What about cruzing town or running up a mountain when it is 110 out with/without a load? Thanks for any insight!!

[rolsmojave3]

A stock truck's max boost is around 18 psi. Seeing you have an automatic, you're boost will vary if your torque converter is not locked. When cruising on the level, you won't build boost.