haha.. mine makes noise too.. braaaaapp! lol j/k
On a more serious note - Might want to include the approximate speed the noise occurs at. Is it at a certain MPH or RPM? Accelerating or braking?
Do you have a track stand? If you do you might want to put the sled up on that and run it with the hood open. Also check your chaincase oil... does it have metal in it?