Thank you for going into so much detail. This will be my first Warbird flight.
Hopefully I've got enough tail-dragger experience with an Edge540, a Phaeton
Biplane, and a DragonLady to make it a successful experience.

I'm glad that you brought up the CG. I don't have the manual, but the first
thread that I listed above indicates that there is some degree of confusion
about where the CG should be. One part of the manual says 3.5 inches from
the LE at the center section, another says 4.25 inches. Which do you fly with,
and where do you measure it from? Perhaps from the notch in the leading edge?

Thanks again, mate. Your P-51s are real beauties

EDIT:
Do you really run your four-strokes without a muffler!?! That is incredibly interesting.
I've never heard of that before. Do you have a photo of the setup?