Shaving the hood is cosmetic only.
You should change the hood a bit so that it breathes from the back instead of the top left. The hood can block incomming water flow and keep it dryer.
You can probably move the hood latches a tad to make the hood seal tighter.
You can add hoses from the hood to the bottom so that the water that does come in is channeled down instead of falling freely from the hood.
Front sponsons will help the ski turn better and keep the nose up in the surf. Tom21 just finished a custom set for the X2 and Surfjet louie has a set for sale too.
Modifying the trim set up will help for freestyle.
http://x-h2o.com/showthread.php?t=19267 Pete did this set up and it's a good idea. It uses a modified stock trim. I forget who but someone is selling a custom trim for the X2 for like $215
I wouldn't suggest cutting your hull until you figure out what kind of riding you want to do. Cutting the hull will improve the turning and the handling, but will cause the ski to handle even more poorly than it does at high speeds already. Make sure your ski isn't going to be for cruising or bouey's before you cut the hull. Cutting it is good for freestyle. Otherwise, go with the front sponsons and a D-cut rideplate.
You could also do the bottom mod like Crab did. It's in the X2mods thread. 24/7 is also making a part like what crab did that's pre-made you can just glue on. It would help with your carving and maybe improve your pop some.
Get something to improve your steering throw too. Aftermarket steering or a modified stock steering arm works.
The rest is mostly engine modifications, which the answer to that question is... as always... the more power... the better...
And as I always say, don't modify the ski unless you know why you're doing it. If you have never ridden a X2, slap it together and try it out for a few rides. Then you decide which mods are going to work best for you.
