What is the difference between these two plugs besides the groove in the electrode? *The 9 tells me that the heat range is the same...why do I need to spend extra to replace the 'S' with a 'YA'??

Im not exactly sure on this but from what i hear, the EYA is a resistor type plug, dont ask me what that means, but i do know that the EYA is much less foul-prone than the ES. Hope this helps...

The EYA is a "anti-fouling" plug. I use the EYA's in my ZRT6 and haven't fouled a plug since. Whether they are a resistor or non-resistor type plug, I am not sure.

both plugs are resistor type thats the 'R' and the same heat range the 'EYA' is an antifouling electrode and if you have ever fouled the 'ES'the 'EYA' useually solves that trail side plug change. I have used both and it is harder to foul an EYA ,you have to really try them in your sled to see,also make sure to use solid terminal type.

When Cat started using the BR9EYA they talked about it at the race school. *The EYA has more surface area on the electrodes due to the grooves, so that reduces the chances of fouling. *They also said the EYA is about a 1/2 step hotter than a BR9ES.

love those eya plugs!!
very seldom do i need to worry about changing a foul plug. *
i can idle the sled for no fear of plug problems

So is it OK to use the ES...ask the dealer (Nielsens, again) to give me a box of plugs with my new ZR800 and didn't realize til later that he gave me ES, and the sled calls for EYA. *Will I hurt anything by using the ES's, since I have a box of them now?

I had a very hard time finding BR9EYA plugs to carry as spares (most auto parts stores don't carry them yet). * Talked to my dealer, and he said the only difference between them is the split in the electrode the EYA has. *He also felt that the EYA burned just slightly hotter than the ES. *Also, EVA plugs can be used (as long as they're BR9). *I think that is a plated plug, not sure with what though. *Bottom line, as long as it's a BR9, you can use it, regardless of the letters after.

same plug, has a solid cap so it doesn't rattle off and has a fowl resistait electrode. *I would use the eya