What kind of ignition system are you running? My MSD setup burn's hotter and i belive that affect's plug burn, the color change on the ground strap look's good. I believe you need to look down in the plug at the base of the porcelin to deterime jetting and like said spec's up higher on the porcelin will show a lean condition with shiny spec's meaning detonation. There are so many different way's i've heard of reading plug's it's hard to be sure and i am no pro by any mean's.