BL Motor Recommendation for Hyperflow 370 EP
 

I need a recommendation for the most powerful BL motor that will fit the Hyperflow 370EP ducted fan assembly...A link to Hobbyking for the motor would be greatly appreciated...I'm relatively new to ducted fans. It's either a 54mm or 56mm (i'm not sure if the I.D. or O.D. is measured to determine fan size). Thanks for any help on this.