Stock Fuel Pressure?

Okay so I have read around for a while and can't seem to find out what exactly my gauges should be reading on a pretty stock mustang GT. Its a 2000 GT with just a few bolt ons and the stock pump. I installed an aeroforce interceptor scan gauge as well as a stewart warner fuel pressure gauge. At idle the interceptor reads 39psi and the stewart warner reads 29psi. When I get driving the stewart warner jumps to around 39psi when giving it some throttle. I've heard about how in vacuum it should read less and at boost it should read more but i have no idea what each gauge should be reading at different points. Will someone please help me out on this?

Alright so I think I found out that 29psi at idle and 39psi at WOT is accurate due to vacuum in the manifold. What I want to know is should the PCM be reading the same thing as the shrader valve location gauge at idle? The PCM always reads 40psi+ at idle and then at WOT it remains at that pressure.

Also the PCM reading from the interceptor sometimes will jump to 50psi+ at idle, at the same time my SW gauge goes up to around 40psi idling. I hear this is the computer raising pressure to prevent fuel from boiling. Is this correct?