what is optimum water pressure at idle through wide open I am seeing over 30 psi at 6000 rpm

ttt

30 is ok,,,but i say 17-25 is optimum !!!!!
Which engine is it and does it have a sea-strainer ???

It is a 598 na, no sea strainer and I am bleading off the pressure out of the back of the intake through 2 #10 lines into 1 #14 through the transom. Oh yeah imco lower and more like 35 psi over 100mph

35psi or more is starting to ask for problems. 20-25psi at WOT is about perfect. Idle usually barely reads anything on the gauge.

What should be my next move to try to reduce the psi

I agree.

if u pick up at the drive, u can block the holes on the lower..if u pick up at the transom , u can file back the pick up.
Other way would be to stick a press relieve valve in the IN line at 25 PSI and dump it over board !

U say, 30 PSI at 6000 RPM,,now u say 35 PSI over 100 MPH.......how high do u rev a 598 ???

I set up a temp gauge and had my passenger watch it we went 106 mph at 6300 rpm and he said the psi gauge hit 35 psi