V20 with Black Max 150???

[spareparts]

make sure you have a Mirage plus and not the original Mirage(it will say so on the prop). The original Mirage ws intended for I/os and can bog an OB, the Mirage plus was a better all around prop and works on OB's better. That 2:1 raito will help the smaller motor(2.0L) push a heavy boat liek a V, just take your time and get the right prop. And like Ferm said, make sure your tach is correct