does anyone use really big batteries?

[ReV:-O]

oh oh i think i found the solution:
EITHER:
a Neu 1521/1D 2900kv on 5s running at 53650RPM,
or
a Neu 1521/1.5D 1900kv on 6s running at 42180RPM.

Both of these are the 1521 motor, and so are stronger than the 1515. with the first option, i'll be getting insane RPM and a powerful motor, so this sounds like the best bet to me!