Hmm, I do not have the top box, but I did order one (takes a while to find one that matches the mount). Anyway, thanks for all the responses! I noticed the sound comes at a certain speed (30-40 mph), regardless of clutch engaged/disengaged. Probably the windscreen. Great idea on the skidplate. I read another thread where the bike was damaged on highway because of lack of skidplate. I'll probably purchase it to reduce the vibes (which honestly are non-existant at highway speeds) and protect engine. Thanks again.