I worked for a company that made spark plugs and at that time there was no difference in any brand of plug ! I made every kind of plug you can name and all of them used the same bonding material as the other , for instance Autolite and JC PENNY plugs were the exact same plugs along with SHELL , towmotor , ETC ! We had two base materials used in them , your regular plugs use a copper & glass mixture to bond the center electrode and terminal inside the insulator or the resistor plug uses a RESISTOR POWDER to bond the center electrode and terminal . Prestolite and Autolite were made side by side usiing the same materials . I donated my vehicle to the research and development team to test different plugs for the years that i worked there and i never saw any difference in any of them . My opinion is one is as good as the other if you get the correct heat range plug !