just did a comparison check of champion to ngk. from what i can make out the y. stands for a projected insulator which will mean that this plug will tend to run a little bit hotter than a standard cj. you could prob. use it if you where suffering from carbon deposits for example. the standard plug though is better suited if your constantly using high revs. regards, Ned.
p s; if you are using this plug beware you don,t suffer plug melt down.