Very good article from a veteran aviator about what caused the Reno crash.
I have to call BS on that broken seat article. The pictures in post #157 clearly show no room or open area behind the seat.
Besides that is where the custom designed cooling system was installed according to the EAA article.
For now I'll go with the black-out after pitch up presumeably because of a malfunction of the elevator trim. Something that has happenend twice before with similar aircraft during the same type of race.