I bought a set of used gauges and there are 2 water pressure gauges. My have twin turbo 454 making about 600/ side with TRS drives. The engines still have the water recirculating pump with the raw water pump drawing water thru a strainer on the bottom of the boat. Also the turbo shields are water cooled too. Do I need to install these gauges? I know on a NA motor a lot of guys will put a crossover on to eliminate the recirculating pump, but I would prefer to keep the recirculating pump to help pump water to the shields and other parts of the engine.

I watch mine like a hawk, they're a great tool.

I would use them. They will tell you things before you have a problem.

A few times I have seen my water pressure drop to about half of normal. The engine water temp was normal and flow looked normal out the exhaust.
Every time, there was a restriction at the oil cooler from sucking in some leaves or trash.

Yes, absolutely. Usually an early warning of something amiss. The two things I'm always watching are oil pressure and water pressure.

just fyi,the circ pump slows the flow of water.do you have gale banks turbo,s?

Same here.

I did not know that about the circ pump.
The turbo system is an original Mercruiser set up that used Rayjay turbos, but the risers for the turbos do say Gale Banks.