Silvaire1 Runup rpm may depend on the prop
Yes that is the reason, mine is a fixed prop and here is a cut and paste from the manual,
(Fixed Pitch propeEler). Aircraft that are equipped with fixed pitch propellers,
or not equipped with manifold pressure gage, may check
magneto drop-off with engine operating at approximately 1800 RPM
(2000 RPM maximum).
I still wonder why the POH says 2000, I fly from grass and dirt strips so i go for the 1800 to reduce the amount of crap i kick up