The OS 8 is not as hot as the Enya 3, and I believe it is 1-2 threads shorter than the Enya plug. I think the McCoy MC55 is the hottest plug I've used, but the 59's are more readily available and are long reach (as are most McCoy plugs) I use the 59's in most of my engines that take a long plug and have very few troubles with them. I've given a few away to guys that use OS plugs (#6 and 8's) that had troubles getting their engines to run right. The 59 perked them right up. I use the Enya 3's in my Enya's, specifically the 4-strokes. If the Merlin plugs were cheaper, I'd consider using them. I usually pay 5-6$ apiece for the Enya 3's or McCoy mc59's.