On the HP thing, its relative to the axle RPM and the amount of power being pushed through it..
But fewer drag racers are using them because of it, and you almost never see road race cars with a 9".
On the other hand, NASCAR uses them... so It must be a reliability thing... Or the need to have easier gear swaps !
The guy who built my 2.5 spent several years on the Winston Cup circuit at a motor tech,
I remember he was one of the first that pointed it out to me, I was going to do a 9 when
I broke my 35 for the second time, he talked me into a 44. He told me there was some ratio
of power loss based on the drop of the pinion relative to the ring gear, that the drop was to
help quiet the gear set.
Its one of those things that you hear about at the race track, Myth and legend! LOL.
Dave