I recently was doing some work on my 2011 Kingpin which involved removing the gas tank. It has an S&S airbox which I did have the top cover off. The bike, 5100 miles, always had a weird noise kind of like a metal rubbing sound but not all that bad. I have tried to trace it before and always come to the conclusion it was coming from the airbox and was just normal engine noise which was just amplified because of the open filter. I took a socket extension to listen for any unusual noise and both cylinders sound pretty much the same, nothing weird or loud. After getting the bike back together and firing her up the noise is noticeably way louder than ever. Had the bike in the driveway and could hear the noise in the house. It was to the point that I wondered if I should ride it. I listened with the extension again and the motor sounded the same as before, nothing unusual so I took it for a ride. Bike runs perfectly fine. I noticed when opening the throttle or when the motor was under load the noise would pretty much go away. Once the clutch is disengaged it would come back like turning on a switch. It seemed slightly better after fully warming up. I was thinking something with the cam chains but at 5000 miles. When I got back I took a rag and covered the front of the air filter which noticeably decreased the noise. Noise has to be coming up thru the throttle bodies. I am stumped. One day not bad the next it is horrible, not a gradual increase. Any Ideas or anyone have a similar issue?