I know this is old, but I hate finding forums that have what I was looking for, but no answer, so I'll add my .02 for future readers.
You have the right ideas with shimming and the snorkel. I agree with DaBlue in waiting for the initial service, that was if something IS off that'd be covered, your unrelated handiwork doesn't give a reason for them to blame you. Also, it'll show you how the bike is going to run once it's broken in and settled, and the plugs will show if it's rich lean, rich or perfect.
Shimming is different than jetting. The shims pull the needles up a tad in the way that would happen if the throttle were to be cracked slightly, but without introducing more air into the mix. I recommend using dial calipers or a micrometer to make sure the needles on each side are raising the needles the same amount, regardless if you use 1 or 4 needles.
There are two jets per carb on these bikes. You have the pilot jet and pilot jet. The pilot jet is like a pilot flame in a stove, furnace, heater, etc. in that it is there for the little bit of initial feed; stock on my '09 is a Keihin 38. The main jet controls fuel in the upper RPM range (the specifics miss me at the moment bc I've spent more time on old stand-up jet skis, so I can tell you those!); stock pilot is a Keihin 98, I believe.
I have a full system Yoshimura and K&N pods, so my bike is moving a lot of air. To compensate this, and maintain the air/fuel ration mentioned above, I moved my pilot to a Keihin 40, the main to a Keihin 110, and I have 2 washers for the needles.
When in doubt, go rich. A too-lean condition will add performance due to the quicker combustion (roughly like advancing timing), but can damage the engine bc it'll be burning hotter. I almost toasted a quad this way.
For Kawaninja's topic, adding teeth will aid in the highway, but take away from lower speeds. Another way is to go wit a slightly taller tire when it's time to change. The difference isn't huge, but would aid in what you're looking for.
As stated above, enjoy the ride for a while on a new bike, and for a new used bike, check it over to make sure the PO didn't do bad maintenance, and then enjoy it for a while as-is. The more familiar you are with your bike, the better you'll know what to do to it.