I'm in the process of building a new car and it will be getting a Lithium battery as well.

We have 1 local racer that has been running one on a sponsorship deal for about 2 years now in a street strip car with great success. It's a 14 volt battery and weighs 14 pounds. Standard alternator, but does take a "special" 10 amp charger that you can get for $35.