Mounting height for Outboard Jet?

[BertJet]

I am mounting a 40HP Merc JET on a 16" Crestliner Modified V-Hull jon boat.
I must decide on the proper height to mount it and just cannot decide.
Too high and I may encounter cavitation (air sucked into the impeller), and too low may decrease top speed, cause more splashing and increase the risk of hitting rocks.
Any body has experience with this kind of issue and can give me advice on the proper height? (My gage is the front of the intake compared to the absolute bottom of the boat).

[Arrowmarine]

I want to say that we always put them with the leading edge about 1/4" above bottom of hull. Dont quote me tho

[BertJet]

Thanks! It kindda confirm what I have heard. I was told by another user to mount the front of the intake flush with the boat bottom. One Merc dealer told me 1 inch below!
Have you had cavitation problem in choppy water?

[Arrowmarine]

Sometimes in tight turns

[cyclops]

On the Delaware River the trends vary. BUUT. VERY small stone bottoms normally UP 1-2" or you drop anchor and do a clean out by going in to the water. Rock and mud, anything goes. Old weed beds are death to all jets here. The weed stems are pinky finger diameters. This from 5 years back in time. New pumps may eat anything by now.