Size motors to use with MMP

My 4.5 with an 1/8th in shaft did 47 in my E-revo http://www.youtube.com/watch?v=nLY9EGOfwOc This was on SPC 8000's 10c 4s. That was on my bashing gears of 14/68, with the low power Novak ESC. With high power lipos, and the MMP I'll bet low 50's could have been possible. BTW I never had this setup have the motor go above 145.
In a mid-sized vehicle, with a big rotor, I think it would be good for any kind of reasonable speeds you want. I'm planning on gearing for around 55 with the Slash.