I am just wondering what do you mean by heat range and hottest burning plugs? I thought that plugs were rated by the length of their tips and how far that they extended into the combustion chamber. The more a plug extends into the chamber the more heat is transfered to it and to the insulator(hot). The less the plug extends into the chamber the less heat is transfered to the insulator (cold). It is bad for a plug to hold too much heat it will act just like a glow plug and detonate the incoming mixture before the piston chamber fills (knock & Ping) eventually destroying your engine.