XJet and Flyer95, I know they run "Nice" on 0%. If I liked just nice, I would have been running 0% for years. Perhaps I should have been more clear on that.

Dar, I’m very well aware of the 0% European engines, that’s why I said "US market engines ". I wish we never had nitro in our glow engines.
I have a Moki "Mark" that likes 5% on a cool day 0% on a hot one. And I had 3 Webra 55s now only two. I lost one when the crank let go several years ago, perhaps due to too much nitro (15%).
I found out the they liked 10% max. At 15% they ran strong but even stronger on 10%, glow plug last much, much longer. (tried every heat range before) easier to tune.

Most of the engines for our market have one head gasket, and if you try to remove it / thin it, the piston is too close or will hit the squish band. (besides the head may leak with no gasket).

I guess what my main question is, is the only thing different between a nitro and a non nitro glow engine is the dome volume in the head?