Thank u so much killer info! :)

This is only my opinion.. I think you'd benefit from higher psi as result of more volume instead of from a restriction. I'd add at least one more stage to your raw water pump like Ray mentioned earlier. Air is a highly compressible medium, if you have an air pocket in a corner somewhere the higher water pressure would make the pocket smaller, the higher the pressure the smaller the pocket, or possibly force it through the system and out the exhaust. Running dumps off the back of the manifold is always a good idea but it will bleed off a bit more of your already low water psi. I'm not sure how you're set up right now but you could run the drive pick up through the intercooler with its own strainer and then use the other one to feed to the raw water pump. You should be able to adjust that thru hull pickup to get any pressure you want and ultimately have enough that you can use a bypass valve to control it on the top end. I like 10-15psi at cruise, and 20-25psi up top.

Right on wow thank u :) :)

I've got Merc single stage pumps in my 604 quad whipples. Pressure fed intercooler. Zero problems. 10-15 cruise, 25 up top. I think pressure relief at the back of the intake is necessary if you don't have a circulating pump. If you are worried about losing pressure route it to the front of the intake.