And for those of us who have English as out native language and still can't follow that stuff

As for the plug, and which to use. The 01 RS250 manual mentions three heat ranges.

NGK: R6120-10.5 (Stock plug)
NGK: R6120-10 (Hotter)
NGK: R6120-11 (Colder)

I stick with the stock plug unless I am using the detonation counter, in which case I run the stock temp plug, but a longer reach body to accommodate the detonation ring.
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Charles Gallant