From a friend's FB feed... He is a Merlin magician for a shop that restores engines for these beautiful birds... This particular P-51 was just repowered with a rebuilt Merlin at Aircorps Aviation in Bemidji, MN - this sequence of vignettes is from the last button up and departure afterwards.
It is great to see this aircraft in such fantastic shape !
You can see some of the other projects on their website... DROOL !