As promised, my particular performance specs incase anyone is interested / building an OC20.
Motor: Yamaha 150hp XCA (2800cc) Digital Electric Control
Prop: Yamaha Reliance 3 blade Stainless 17m 14 1/4
Trim Tabs: Bennett Bolt 9x12
Crew: 3
Fuel: 150 Litres
WOT: 40 Knots at 6000RPM
Cruise: 20-25 knots at 3400-3800rpm
Fuel: 17-20 Litres per hour at cruise
Just did a 150km round trip to the top of Fraser Island and we only used 74 Litres of fuel total.