The 12 bolt design is a bit more efficient than the 9". Guys who use that are typically lightweight, not tons of power and willing to do whatever it takes for the last bit of performance. Think Comp.
Anybody ever seen a definitive/scientific test of rear end drag? Never heard of one. There was a magazine that did some tests, but as unscientific as it comes.
In fact, that took so much effort I am astounded that they did it when it all could have been done on a bench.
As such, this power robbing 9 inch story carries on and on, and will never end.
I find it amusing.
