Like all good things in life...buy the best cry once.
I used to road race motorcycles, and by far one of my best sponsors was
Shorai batteries. Lithium ion as opposed to lead-acid.
This is personally what I run my HDS 5.2 on, but you can go smaller.
http://www.shoraipower.com/p-155-lfx18a1-bs12.aspx
I ran the tiniest 12V in my race bike, as it was just to start the bike over.
No signals, lights, horn or anything like that to power, and its all about weight. 5% reduction in weight is the same as a 5% increase in HP, right?
18 A/hrs. and the thing weighs 2 pounds. Compare that to a regular lead-acid one and that'll be 7/9/10/12 A/hrs. and weigh 6-8 pounds.
I've mentioned these batteries to CJ at OEX MB. I'm sure he can order these as people want them, but doubt he'll stock them due to the cost factor.
Personally I think it's awesome. I can go for a few trips w/o having to charge it. With the HDS-5.2 using .75 A/hrs, you've got some serious juice to carry you through multiple trips, and at 2 pounds, you can really feel the difference .
RobFish