I've read some are using the GRP/ninja plug in novaroosi engine. I've look at these two plugs and they very different. The Grp plug does not sit flush in the burn chamber like the nova plug does. I also read the Ninja engine could not use Nova plugs. Then why would a GRP/Ninja plug work in a novaroassi engine. To me the GRP/Ninja Plug is not a suitable replacement for a Novarossi plug.