1994 2.5L Merc XRi..anything somewhat easy to do to boost some HP

[Luke]

motor runs solid but the boat is heavy and could use a little extra ummph.

there anything that can be done? heads maybe?

serial..0g105525

[John Jackson]

Heads and fiber reeds will give a good bottom end and mid range bump, but not much HP. A 200 tuner and cowl mod will each give 1-2 mph. But even with all this, a stock 175 will be stronger on top. It really is cheaper to upgrade HP than to build it.
If boat is rated for enough HP and can hold it, a 3.0 motor would be the way to go.

[Luke]

should have put it in but motor is a 200hp XRi

[John Jackson]

Good reliable motor, but to make significantly more power, you will need porting (port timing is the restriction), which means RPMs at a lever that you will need to installed forged top pin pistons and probably start premixing, just to try and live.

[CAC29]

There's really no limit as to what you can do. But the real question is do you really wanna do it? There are mods out there that are good for your motor. But you reach a point relatively quickly, where, you will make mods to your motor, that will give you more power but will shorten the life of the motor in the long run unless some serious steps are taken. In my opinion, if you're really looking at 35-40+ HP you're better off looking at a 225 promax powerhead. It's a fantastic motor. And will make 245+HP. And very reliable. It will bolt right up and plug in to what you have. However if you are set on your motor, you can do reeds, shave the front half .050", add a 1" reed spacer, shave heads, and the list goes on. But I wouldn't really do much more unless you take on a full motor build.