The “Miller plus plus” is a double back somersaults with 5 twists. It is sometimes also called “Thriller” or “Turgeon”.
A double back with four twists is a “Miller plus” or “Killer” or “Polyarush”.
(I’ve never heard of most of these names.)
Of course all this is academic because who could possibly compete skills like those?
Jason Burnett of Skyriders in Toronto, for one.
Click PLAY or watch double layout with 5 twists on YouTube.
I recall Boris Verkhovsky teaching us twisting years ago with imagery of turning a hula-hoop, or steering wheel.
Jason Burnett takes that concept to the MAX, holding an exercise ball throughout a routine.
Click PLAY or watch it on YouTube.