I don't see that it matters what you use, as long as it's the equivalent plug to what's specified. Lots of folks say, use Japanese plugs in Japanese engines, American plugs in American engines etc. I blasphemed and used Autolite in my Kawasaki, and it's running just fine. Does it run better than NGK, I can't see that it does, I can't tell any difference between decent plugs. I've read where some say one brand or the other simply won't run in their engine, who knows, I can't imagine it's a big deal.