water pressure

I have a 2012 Mercury Optimax 115HP 2 stoke. Until recently when a friend pointed out what it was I never noticed that I have a water psi gauge on my boat. The gauge reads 0 to 40psi, what is the psi suppose to normally read during idle or wipe open throttle? I can't seem to find anything from Mercury with the specs for this gauge.

[img]https://www.manualslib.com/manual/824123/Mercury-Optimax-115.html?page=291#manual[/img]

Idle: 1-3 psi

WOT: 12-23 psi

Thank you so much T bird!