Heh, I just went through all of this with my Hyper 7 conversion. The thread is right here:
http://www.rc-monster.com/forum/showthread.php?t=5302
A gallery of pics of the conversion is here:
http://gallery.rctrack.info/sleebus_jones/Hyper7/
I went with the 10L motor for mine, and the MM controller. I'm running 11/46 right now. With the 3S 2500mAh Apogee pack in there, my speed is right around in the 26 mph range. I have put 12 cells on it, and that puts the speed in the 34 mph range. With both of these combinations, the motor and ESC stay cool. Running 12 cells, the motor gets hotter than the ESC, so I'm going to go up a few teeth to 13/46, which will put me right at 40 mph.
As it is right now, with the 3S in there it'll spin all 4 panthers on concrete with no problem. The 12 cell is pretty silly, but it's heavy (1.6# of batteries) so I'm planning on going LiPo to shave weight and add power. I'm looking at the maxamps 4S 4000mAh pack for that.
Sleeb