so, I should give you a little background story.
I fly primarily FSX, and lately I've picked up the Reno Air Racing that you can do in the game, which counts laps and times, in the practice mission.
I love air racing as there is more to it than racing cars.
So I downloaded a freeware P-51, designed to look like Race 38, Precious Metal.

out of the box it wasn't doing so well. A low roll rate coupled with some improper engine and prop tuning ended up with a plane that could barely handle the pylons at little more than 400 MPH. she flew so slow and so improperly that I took it upon myself to make her fly right, under the speeds I knew Precious could fly.
so I did. I tuned the engine up to its proper horsepower, the proper piston displacement, and everything else, and then I took some cues and hints from the RealAir Spitfire, which has a contra-griffon powered Spitfire for the propeller stats.
The creator, Bill Cook, used stock P-51 wing geometry, so I modified the wings in the file to match their actual statistics.
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all that took about a week, between work and being social.
After all that though, I flew the Reno practice mission to find that Precious Metal BOMBS around the pylons at speeds of 465-470 MPh and times of 1:04 to 1:06.

A happy coincidence, I found, is that under 1000 RPM on the ground, the engine coughs and stalls out.
Now to create my custom paint job.
EDIT: I am going to try contacting the pilot/owner over facebook to get some more data about the engine. Specifically the boost pressures and so on.