Heres the spec for the recommended batterie pack

â–*Capacity: 2200mAh
â–*Number of Cells in Series: 4
â–*Rated Voltage: 14.8V
â–*Max. Charge Voltage: 16.8V
â–*Min. Discharge Voltage: 11V
â–*Maximum Recommended Charge Current: 2.2A (1C)
â–*Continuous Discharge Current: 55A (25C)
â–*Discharge Lead: 12AWG 3.1" (80mm) long wire w/Deans Ultra Female Plug
â–*Charge Lead: 24AWG 0.8" (20mm) long wire with Balance Connector
â–*Pack Dimensions: 103 x 35 x 32mm (4 x 1.4 x 1.3")
â–*Weight: 8.2oz (233g)

So if you could find something with bigger Mah but about same weight, that would be alright.
juste like the Thunder Power Pro-Lite 4S1P 2600 (238g), altough it's a 20C instead of a 25C.

If we do:
Great Planes Thunder Power
2.2AmpX25C=55Amp max 2.6AmpX20C=52Amp max

Tis would be about the same, but in flight time I don't know