Welcome!...
Welcome to the forum. You've made a wise choice in the Sea-Doo's. They are one of the worlds leading PWC's in use today.
I don't know what to tell you about making your Doo faster. Unless you want to start a mod, if not, then you should find happiness in what you have. The reason I say that is because, like everything else, when you first ride it, you think "wow, this thing is fast", but after riding a while, you feel it isn't as fast as it once was. This is normal. Once you start making changes to the OEM configuration you will, at some point, start running into a finanicial nightmare.
With the age of your Doo, it's possible your wearing ring is a little out of spec or your impellor has some nicks and dings. Or if your not reaching max RPM, you can fix that too. These are the only things I can think of that you need to look at before you start doing any other modifications to your craft. There are aftermarket impellors you can buy that will make you go faster but remember this, to go faster in the top end, you'll lose the hole shot in the bottom end..........:cheers: