I still have the stock Saito plug in my .56 that was in it when I bought it, and I don't know why a Glow Devil 4 stroke plug or even a Glow Devil R/C long wouldn't work. Mine runs fine after three years and I haven't had to set valve yet either. If the engine runs fine, I figure why bother? For what it's worth, I have mine in a Score that weighes 70 ounces, and I'm running Bob Reeves' screw set up, and a regular plumbed plastic 4 ounce Sulivan tank on muffler pressure. For prop, I have been using 13-7 Rev-Up or 13-7 Vess at take off RPM betwen 7800 to 8000 RPM. I'm full out on lines at 70" handle to centerline of the model and lap times between 5.3 to 5.5 seconds. Been loving this combination since I got it all figured out, and just need the spare time to build another model for a Saito .62 I have.
Type at you later,
Dan McEntee