Mild Deto will yield a slight sandblasted type appearance on the edge of the piston dome with extremely high temps being transferred to the piston, a slight swelling of the piston will occur that may result in scuffing. Major Deto can usually be heard by the operator as a knock, ping, or miss when on the gas at high RPM at high temps. A noticeable sand blasted affect will appear on your dome, your piston will swell and typically a dime sized chunk of your dome will break off, usually on the exhaust side of your dome. Alot of the failure pics I see show all the above systems. I ride with alot of guys running alot of Pro's, no one has had any issues over the last 2.5 seasons except myself who lost a motor at 2,300 miles. I am the only one in the group who would run on the premium setting when I was supposedly buying pure gas, everyone else is paranoid and playing it safe, maybe I should have played it safe also. Has polaris come forward with anyone and said that it is postively deto, maybe I'm barking up the wrong tree. They replaced my topend with no questions asked, which was great, but did I create the failure.