I got a hold on Shorai Battery, It is Lithium battery. This thing is super super feather light, and damn small. I had to figure out the right padding in the compartment for my seat to bolt down good. But I really like it. It will hold charge longer than regular acid battery. When I start my bike, it start a bit faster with higher rpm. Mine was $99 plus $6 shipping. They are completely sold out. Shorai is making newer improved one, to be available in mid April. I am a daily commute rider and no track involved. So what they had right now was good enough for me.
This battery can sit for a year and still works, according to the manufacture.