I had an Autometer SportComp electronic fuel pressure gauge on my old Civic and it was pretty damn accurate. Also note that the Autometer fuel pressure gauge isn't an analogue electric gauge, it's actually a digital unit with separate brainbox for the sensor and gauge to interface.
More than likely your fuel pump is just wearing out. Your idle fuel pressure seems about right. With the vacuum line disconnected you should see 43.5psi. If you're boosting 12-14psi (Stage III) you'll see 56-58 psi.
"The 300ZX Turbo is a dance; it's a song; it's rolling, roaring automotive art. There is no color that doesn't suit it. There is no mood-lifting chemical substance it can't replace." - Automobile Magazine
