What do you mean by hot rodding? Lot's of wheelies or are both tires on the ground? Also, is the buzz like grabbing the bars out of your hand or just high frequency annoyance? Or somewhere in between?

Whichever, this is probably not serious, and sounds like bad wheel bearings actually. Does the front end feel a bit less planted??????? How hard have you been landing the front wheel? Mine crapped out at around 15K (no wheelies, but plenty of potholes and high speed)

To get back to where you may need to be, perhaps consider:

-Replace steering bearings, check race for straightness. Why? Cuz they are crappy quality in "hotrod" applications.
-Replace wheel bearings. OEM's are not top quality, either. Especially if you've beaten the front end.
-Pull apart forks and inspect the springs and listen for any looseness/feel for roughness of the tubes. Consider replacing springs with aftermarket 'cuz if you're a fast rider you'll very much appreciate the difference, especially if you're over 190.
-Replace fork oil. Silkolene comes highly recommended, I'm running it now as are other FJR pilots. If you've beaten it hard, the stock stuff is mud.
-Put all front suspension settings back to stock. Now Put rear preload on hard. Rear rebound at 6 clicks from full hard. Do not ride with 4 clicks or less.
-fork preload-increase 1/2 of a bar. Get them both as equal as you can. Fork compression harder 3 clicks from stock. Fork rebound harder 3 clicks from stock

Not sure if you have all the tools, knowledge, and links you need for info on how to do all of these yourself and save $ and pain from the dealer experience. If not, get a moto head to help or post where you are, maybe one of us can help.

Call CBR bearings (do a google for info) for the bearing kits, they are top notch.