I got the Ballistic EVO2 6 cell from Rider's Discount. There's a thread for them here.
http://www.kawiforums.com/riders-dis...batteries.html
So far so good, but I've only had it since Friday. Battery is tiny, around half the size of stock. I cut up the foam it was packed in to take up the extra space in the battery box.
Rider's Discount was great to deal with as well. I called and left a message on Wednesday and got a return call later that day. Battery was shipped on Thursday and I received it on Friday. They're in MI, I'm in Northern Illinois.