The only OS plug I'll buy is the Type-F for four-strokes. To me, nothing touches them.

For two-strokes, I'll stick with Tower, Thunderbolt, McCoy, Fox and a few other housebrands. Since I no longer run expansion chambers on my two-strokes, just about anything will do. Putting an OS two-stroke plug in a two-stroke engine that I use for sport flying is a waste of money, to me. YMMV