You can use any number of packs/cells , but it is customary to use 1 or 2 packs totalling 8-24 cells. I normaly use the max number of cells that esc will handle.

get a vxl and a 3s lipo. youll be running faster and longer than you ever imagined

That would not be a good choice for an e-maxx. A larger brushless system would be in order.

my set-up...

E-Maxx.
VXL system with Integy motor fan heat sink.
MaxAmps 3s 5000 lipo.
RPM Monster claws wrapped in Pro-line badlands.
CVDs all around so i don't keep ripping my axles apart.

performance...

Shames every T-Maxx 3.3 its gone up against. wheelies at any speed. backflips on takeoffs. against a Maxx with the novak HV4.5 system and 4s.... im faster.

temps are fine and run times last anywhere between 20 and 25 minutes. doing a speed run, my tires ballon so much that they rip off the rims and even the foams blow out...