I was taking a test drive to sort out the new Blue Thunder intake and 650 Holley today. About 5,000 rpm there was a loud bang and it sounded like I'd lost a lakes pipe cap. Pulled over and found the broken end of #2 spark plug hanging on the plug wire. Drove it home and finally discovered that the center of the plug had blown out and the outer part where the wrench goes was still in the head. Pulled it and got a new plug. Had to pull the header to see what was going on and don't have it totaly back together yet. Mummert heads and Champion RC12YC plug. Anyone else ever had this happen?