"To start with NO, the 25 was
"To start with NO, the 25 was the most horses Merc squeezed out of that powerhead (about 24 cubic inch motor).
You can "detune" it to make it a 20 or a "super" 15 model but nothing more.
The 30 horse (twin) shared a powerhead with the 40 horse (twin) and used a 39 cubic inch block.
Simply bolting on a 30 horse carb will do nothing but cause some flooding.
"Any other suggestions to make me run faster?"
There is nothing you can do to that motor which will make a "noticable" increase in your top speed.
You need to increase horsepower by 50% to increase your top speed by 15%.
So say you are getting 25 mph at present, by strapping a 30 horse on the back you might make 28 mph and a 40 horse may get you over the 30 mph mark - of course both of those models tip the scales about 50 pounds heavier than your 25, so you would lose a bit of the potential speed due to the extra weight.
Alternately, you can run as light as possible - take nothing with you that you don't need and leave the passengers on the dock.
You can spend money on fins/hydrofoils, additives, a stainless prop and any of the thousand other products out there that claim to increase power and speed and the net result will be less money in your wallet with virtually no improvement to your top end.
If speed is your goal, remove the motor and strap on one with "gobs" more horsepower. If you are already at/near your max horses for the rig then unfortunately, that's about as good as it gets...."
