Nothing special about the motor - It just has a huge *** gap.
The 'special' thing is the coil if you want to call it special. Instead of putting an indent or a gap in the motor (top plate section) like xbl^2, they did it with the coil. Basically created the ends thicker then the middle...and imitating xbl's good parts....
But....then you get into issues of higher cost of production due to the coil being a PITA to wind...and you can't make it a dual, because the gap would have to be twice as wide as it already is...in turn making the Q in the 1.xx++ range..and having even less bl (even though there would be more wire in the gap)...
I'm glad people (besides me) are seeing what will go wrong with this sub, if you push it just a little too far it gets *****y quick...