How many miles do you have on the bike and do you have the chrome radiator guard?
Also, a better discription of what you're hearing than buzzing or vibration noise would be helpful. Does it sound metalic? Is it constant or intermitent? Does it increase in intensity as you increase speed between 2300rpm and 4200rpm? Is your tank loose; i.e. if you grip it in both hands and try to move it does it move? When you hear the noise can you place a hand on the tank and see if it stops?
I know these things can be incredible annoying; since most of us haven't experienced what you describe I'm hoping there is a simple cure/solution.
"Do what you can, with what you have, where you are." - Franklin Delano Roosevelt