ZRX whistle/rattle when revved.

Hey guys. Just looking for a bit of advice about the noise coming from the bike. It's kind of like a whistle/rattle only when revved. Doesn't matter what part of the rev range but it happens even at low blips of the throttle as well.

http://youtu.be/av3QS90yyxE

If you know what it is or could be please let me know. I have pulled the front cowl off and checked most of everything under there that could be loose.

Sounds like and exhaust leak. Check all the points where the exhaust slips together an see if you can find any carbon build up.