Sounds to me like the more you pay for a plug doesn't necessarily equate to actual extra performance. At least some of the threads I've read suggest so. I've been running what was in my Dog when I bought it. I assume it's stock, Champion RN12YC. She runs good and I'm firm believer in the philosophy of if it ain't broke, don't fix it. I do pull my plugs once in the while and look for proper color and gap. :2thumbs:Until I read something firm here in the forum to the contrary, guess I'll stick with what I've got.