I think it was a .60 suggestion when Schluter then robbe changed to a .90 suggestion.
I'm not for certain. don't have the full history on the whopper, although I have a
review article by larry jolly somewhere...
not sure about the semi-kit designation....
Whopper always sounded to complicated to mess with, pre-spin and all that.
Experience the G3PO tells me that simple can work well.
The only times I wished i had pre-spin was with no wind on grass takeoffs....
mickey