I buy my champion plugs from the dealer, a few years ago I picked up 4 of the remaining plugs a dealer had on the way home from work, stopped at a parts store for 2 more and when I compared them they were different plugs, same part number but different construction. The parts store ones had thinner components then the dealer ones. I used them anyway, when I changed them a year later they dealer ones were at .055 gap, the two from the parts store were between .060-.065 gap. I only buy them from the dealer now... Knocking on wood, I have never been screwed by OEM parts, can't say that about aftermarket...