^ You could get away with running less than 5000 mah and 40C...the important thing is fitting inside the chassis slot - unless you are making your own mount then you can run as big a pack as you want. more mah and C rating the more power/runtime you will have.

A 3s (11.1V) capable esc is a cheap upgrade and will really increase power and speed, do it if you can, the stock silver can motors will handle it.