It's all about the size of the prop you can spin! If you can spin a labbed 32 at 5000 rpm (and slippage can be kept to about 15% which is average), you can hit 80. If you can't get that labbed 32 to 5000 rpm, then you need a smaller prop and you will not hit 80. Or get enough power to spin that prop. Anything smaller than a labbed 32 at 5000 won't hit 80 with a standard 1.5 ratio bravo outdrive.