Hey buddy, welcome to this awesome forum.
The best bang for the buck, as stated before, is to keep it stock, and not worry about making any changes. These boats came with either a NA (naturally aspirated engine) producing 155 HP (which is what I have), and the monster SCIC motor, making a lot more ponies. These engines are the same size, but the internals are not the same. The NA motor has higher compression pistons, since it draws it's air through natural induction. So, as the pistons go down, they suck air. Because of that, the pistons are flat, and produce their own compression. The Supercharged motor shoves air into the intake, so as the piston moves down and sucks air with it, the super charger forces even more air into the cylinder, and gives you more air (Oxygen, really) in that same amount of space vs. a regular NA motor. Because you have more air coming in, the pistons are caved in a little, or else the compression ratio would be like 20:1 (maybe I'm exaggerating a bit). So, the more air you need to force into a cylinder, the less compression pistons you need, since you're forcing air.
So, with all that said, if you take the supercharger off, you'll run like poop.
You have a great boat. 15 feet, with 210 HP. That's incredible as it is. Just to let you know, most bow-rider boats have a 135 HP engine in a boat that's 17 feet long, and weighs about 200 Lbs. Your boat weighs probably 1400 lbs, and has a LOT more power, so be happy with it.
My advice, is if you have no problems with the boat, no issues, then DO NOT TOUCH IT. the boat is tuned pretty well out of the box, and it usually doesn't need any fiddling with. Just take it out, and enjoy the incredible engine, and ridiculous maneuverability this boat gives you. You really don't need that much power, but if you're towing a skier, having the extra power helps him/her get up quicker, and it helps the boat plane better, too (get it's nose down while running).
Enjoy the boat, brother. It's a blast!!!
