Raptor,
Thanks for this latest addition to the Mustang stable. Despite the lighten armament I've been enjoying flying the Mustang Mk. I. I think I'd like it better with the 4X.50 & 4X.303. I'm looking forward to the Mk. Ia and A-36 versions too.
I recently noticed that the manifold pressure for the engine in the Mk. I is the same as in the P-51A ... both register about 55-56 inches. While this is correct for the P-51A with it's V-1710-81 (my books say it should be 57 inches, but 56 is close enough), it is not correct for the Mk. I as it had the V-1710-39 which was rated at 44.5 inches of manifold pressure. This is shown on the page below under the heading "V-1710-39 performance and operating limits":
However it does show the maximum limit as 46 inches on the next page (below). Also included is the data for the V-1710-87 and V-1710-81 engines.
Hope this is useful. I really appreciate your efforts for this very important bird ... THANK YOU!!!!!