Im running the BP21 on my F3A shockflyer. Ive got nothing but good stuff to say about it. Awesome durable little no frills motor. Like a Timex watch...just keeps on ticking. Ive got two of them. Ive found no reason to buy anything else. At 24-26 bucks a pop, they will perform just as well as a Axi 2204 at 1/3rd the price.

Durability is TOPS. Ive smacked mine in countless times, managed to dip it in a pond, hit a powerline multiple times, never missed a beat. Still working great.

If your looking for a cheap alternative to an expensive brushless motor, the BP21 is it.

11.3oz of thrust on a 7.4v 730mah lipo, and it will run for close to 15min.
21 oz of thrust on a 11.1V lipo. Hot little motor.

Im running a APC 9.4 slowflyer prop on mine. It seems like the best one Ive found. Smooth, and powerful.