I apologize if this has been asked and answered already, but do we know if any significant modifications were made to this P-51 just prior to this race?
@Flight Safety. Post #67 references some changes through June 2011.
AP also has story on the wire entitled "Plane in NV crash had 'radical' changes to compete" -- though bear in mind how accurate the media can sometimes be on aviation issues.
News from The Associated Press