Well, first of all get the CFS3.1 and 3.1a patches at http://www.microsoft.com/games/combatfs3/
It will update the P51 cockpit, add level bombing and certain gameplay related fixes.
The P47 has unfortunately not been updated AFAIK, not by an official patch and not by the community.
However, if you feel obligued get yourself the Aircraft and Vehicle SDK at the very same site.
It contains the P47 as a sample source file.
If you think you can handle a 3d design application you can give it a try yourself