I've got the same problem (I think) with my 96 GS-R. Heat shields have all fallen off or been removed, I believe. I just recorded an MP3 of the sound -- can anyone who's solved this problem let me know if it sounded like what I've got...?
My rattle/buzz
This is revving from about 2000rpm up to 4000rpm, and then back down. A buzz at 2800 or so, and then the much more annoying sound from 3200-3500...
Thanks in advance!