RE: fastest motor for electric pylon
The Neu motors are arguably the most efficient motors in that size. You can also look at Hackers and Lehners, but they generally cost more. The Astros and Megas are great bang for buck and they work very well, it's just how far you want to push the limits of performance. On the less efficient motors you have to watch out for heat build up; you can potentially burn up a brushless motor if you run at high power for an extended period of time. With lipos the threat is very real.
What is smoking fast for one guy is ho-humm for another. Like Dolanosa said, how much you wanna pay?