If a modification is permitted by the rules and the question is whether or not to have it done to improve longevity, that is one thing...

It seems to be an entirely different kettle of fish to define a change as a "safety modification", to rationalize the legality of a modification not specifically allowed by the rules.

Is the hardened gear a case of the first or the second?

I am NO rotary engine expert and maybe I am being pedantic (wouldn't be the first time!) but heat treating is a modification isn't it? What have I missed here?

Kirk