Drift boats weren't really designed to be motored, so the more horses and weight you put on, the more water you push with out gaining any speed or efficiency. When you're not planing, the only factor that provides thrust is displacement, not horsepower. Check the specs on motors, and you'll find certain models sold as both 6 and 8 horse, 8 and 9.9. and etc. (Check displacement, weight etc, for like models). The carburetors are set to provide higher rpm ranges, so a motor running say 500 rpm faster on step is producing more horsepower, but will provide no more thrust than the lower rated motor used as a kicker.
You can often save money when buying your troll motors using this system. You know you're not going to plane your 20 foot salt water boat with a 9.9, so check if the 8 horse is the same power head. Not all sales staff will share this with you, as the cost is greater for the "bigger" units.
Weight perched way bank on the transom will be more of an issue on drift boats than one or two horse power. Try to use a long hose and put your fuel tank forward.
See if jcalderon is still selling his 8 horse Suzuki injected, long shaft motor. I know that model is the same power head as their 9.9 model.
Add planing fins to the cavitation plate to reduce transom dipping.
