I bought a 2s 4000Mah protek pack($59.99) from amain about a week or 2 ago as a intro into the whole lipo scene, and that thing is unbelievable I put it in my brushless stampede and it'll wheelie on demand and as far as run time i'm bored of running the car up and down the street before the pack runs outta juice. it's wicked awesome, i'm almost afraid to see what a 3S pack would do to my poor little stampede.