I too run NGK in all my toys and I think the only reason why I run NGK in all my toys is I have it in the back of my mind--if it works good in a 2 smoke/stroke, it'll work even better in a 4 stroke. With that being said I also have to say though if your machine is running right you'll never know the difference one plug from another(brand wise), the only thing Ive noticed is on sleds with NGK is that the EYA's are cleaner burning then ES's but I THINK thats because the electrode is finer so it burns its self cleaner easier.***I did buy off of ebay a 3 oil filter&spark plug package deal and the plugs were champions, I haven't used them but thats what came with the filters so other people are using them. Guess its all personal choice.

 

I try to change them out once a year whether it needs it or not, cheap insurance.