The Astro 020 #803Z works well with MAS 5.5x4 prop. I'm using a Hacker 30A esc. This has been a very solid combination.

Model Number p/n 803Z
Motor Name: Sensorless 020 Motor for Zagi
Gear Ratio: Reversed
Stator Winding: 5 turns # 20
Stator Resistance: 0.075 ohms
Speed (Kv): 2567 rpm/volt
No Load Amps: 1 amp
Best Battery: 7 to 9 cells
Best Prop: MAS 5.5x4
Prop RPM: 18,000/21,000
Motor Amps: 15 to 20 amps
Power Input: 125 to 175 watts
Motor Length: 1.75 inches
Motor Diameter: 0.980 inches
Motor Shaft Dia.: 1/8 inch
Prop Shaft Dia.: 3/16 inch
Weight: 2.5 ounces
Control Type: Sensorless
Control BEC: 5 volts @ 1 amp
Control Mosfets: 12 Mosfets
Control Weight: 1/2 ounce

Regards,
TX