Originally Posted by Duster_360

What're you going to run this in - brushed or brushless? If its brushless, you need to figure the impact based on motor's kv - if its something like a 5700, a 3S (11.1v) will make it a lot faster to the point it will be hard to control and possible exceed max motor rpm. You're prob going to need a separate low voltage cutoff to protect the lipo from being overdischarged. There are add on LVCs available.

You would see a performance gain with a 2S (7.4v) lipo thats more than just the weight. Lipo maintains voltage better under load and your car will have that "fresh off the charger" NiMH performance through most of the charge. A 2S fully charged is 8.4v, a 3S fully charged is 12.6v.