So if I understand this right and I doubt it at this point 
My modified engine builds power at higher RPMs than stock, thus I should go with an impeller
that would actually let the engine rev higher rather than bring them down.
Where's the experts here 
Is it like putting 3:73 gears in the rear of a mustang to let it goooooo when you install the B cut impeller??
Is my rambling even making sense
NO!
Let me see if I can say it without tripping on my tongue....
A pump will absorb the horse power you put to it, it will convert this HP to pressure, this pressure is then sqeezed tighter to create a velocity (speed of the exiting water), the speed and volume of the exiting water is what makes the hull move....
Now that the physics are written (sort of)... the hull speed cannot be higher than the water exiting velocity...right?, so, it would stand to reason that the more pressure the pump makes, the more HP it will absorb, or vice versa, thus ending up with a higher exiting velocity and making more speed.
Now think about all of that together, if you have a tremendous amount of volume, but slower velocity, the hull will come out of the hole pretty good, but will lack in the top speed area, if you have super high velocity speed, but no volume to brag about, it won't plane for crap and may not be enough water to make it very fast either, so you want to be right in the middle of the two.
The pump will take a tremendous amount of HP, sort of like a hydraulic brake, spinning it faster
should raise the pressure, sometimes the engine torque curve is different than the impeller pump curve, not allowing the motor to make its top numbers, that is when you would change the cut of the impeller, to obtain peak HP at the RPM the motor is happy
Sometimes the HP is at 6000 rpm, well, that means you need to figure out what HP your talking about and make the adjusment to let the engine get there...Otherwise the motor will lug and you have wasted your effort...
The only difference in an "A" versus a "AA" is longer impeller blades, the pitch stays constant, so simply stated it takes a smaller "bite", that is why the impeller choice is so "odd", a propeller is different in that they have different diameters
and different pitches, pitch adjustment will move the water farther per rev. whereas the diameter will allow slippage to get to the desired RPM quicker while planing..
I hope I did not confuse the issue (I talk with my hands and that difficult to get to a keyboard
)
GT
