i ran a 3s in my sprint 2 flux touring car with a 5700kv sidewinder. i find it kind of tough to use ALL of that, honestly. 2s is more managable for me. but i guess for a speed run 3s the way to go, if you're able to keep the car going straight. maybe with a stampede it's more controllablei do not know. but i'd start with 2s. i get my batteries from hobby king. i think you can get a 2s 20-30c 5000mah for less than, or around, $20. go for the us warehouse if you're here. WARNING i think some sidewinder setups DO NOT take to 3s, according to the manufacturer. check for yours.