i dont know which page it is on, but someone a while back actually measured out all the different plugs, the only one that matched the grp plugs were the os plugs, i havent had a issue with a p3 i change mine out around a gallon of fuel, havent had one go out on me during a race, if you run the grp plugs make sure you run the 4 the engine acts a little finiky with colder plugs