my 2000 boss does that too.. and has ever since like a month after i bought it... i tried checking out the tranny to see if anythings wrong in there, but it all seemed alright. its been almost 2years since i got it (it was a very early 2000, i got it in summer of 99)nothing seems to be bad, and im pretty much getting used to the sounds.

 

Yeah, I knew the trick about giving it a little throttle on the down hills to get some engine breaking. It was in the owner's manual for my golf cart, so I tried it out on the quad, and it works well.