Was the battery fully charged up?
I put a 7.4V 15C 1200 mAh lipo in my ex-girlfriends clearsoft "DPMS Panther" and it was a lot snappier than the included 7.2V or 8.4V. In fact it was more like a 9.6V at the start of the charge but near the end got sluggish and acted more like an 8.4V.
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE