Older Saito engines had literature that mentioned Saito P2 and P3 glow-plugs. I was unable to distinguish between P2 and P3 plugs, and they seemed to be identical to the US-made McCoy plugs. Until recently
engines sold in the US had Hangar-9 plugs (HAN3010) that also seem to be made by McCoy, but new engines now have the HAN3011 plug that is made in Taiwan and looks like it is from a different manufacturer. The
Thunderbolt 4-cycle plugs (from HobbyPeople) also seem to be made by McCoy. Many people report improved performance after switching from the Saito plug to the OS F-type plug - if you are having
trouble with your engine first try installing a new OS F-type plug. However, I have always been able to successfully use the standard plug that came with the engine with no real complaints, however I now
mostly use only the OS F-type plug out of habit, not because others don’t work. It is best to keep an open mind regarding plug type because the fuel type and prop has some effect on the optimum
plug, and you should be prepared to try different types if you are not happy with what you now use.
The English MaxFlash No7 plug seems to work as well as the OS and Hangar-9 plugs. The MaxFlash plugs come in a variety of heat options; the number 7 version, which is the hottest, seems best in my experience for
the Saito engines, although you may like to try a cooler plug, ie No 5 or No 6 if you use fuel with lots of nitro.