It's funny you should say that. We were at the local track this weekend and the #5 plug we had in the GRP died. So we go to purchase a new one and they are all out. Hmm! So the guy acturally went and matched the P3 up with the calipers and a ninja plug and they are very, very close. Put the P# in and wow what a HUGE difference it made. The cold plug was coming off with temps of like 220-230, after a 10 minute main, the motor came off at 187 and was humping dirt big time. So it's safe to say that the change was awesome!