Donzi quicksilver
 

1988 Donzi ragazza, 7.4 @ 330 hp, with a quicksilver 14 x 19, 4 blade S.S. prop.
I get 41 mph @ 4200 rpm, 2 people 1/2 tank (35 gal.), boat listed weight is 4,500#
With this engine and boat weight I should be able to get more top end.
If I go to a 21P that will drop my rpm further out of the range
If I go to a 17P that will put me in the range but will not increase my top end
Is it the style of prop or am I missing something else.
Any input would be appreciated