Low Water Pressure

[offshorebay]

2006 60HP 4stroke water gauge read 25 on startup at 5000rpm. pressure
now is 18 at 5000rpm. Replaced water pump kit but pressure still 18 at 5000.
Would salt build up cause this.
Would Thermostat have any bearing on this?
motor is used in shallow salt/sand water

[boats.net]

Check the thermostat but it probably wouldn't affect pressure. 18 psi is very good and nothing to worry about.