Welcome to Iboats,
If you would start providing HP and brand OB would be very usefull.. No matter which brand or HP OB you use as a kicker, generally speaking you need to perform a prop maximization for OB to work inside it's wot rpm range, preferably towards the max wot rpm side. For that need to install an induction tach, go for a wot spin lightly loaded to check max achieved wot rpm, then can go from there maximizing a prop pitch to better "push" larger boats at fast displacement speeds.
Happy Boating
