Bought a free floating disc brake conversion kit for my Y-11 from Chasertech (chasertech.com). I've seen conversions kits like this running around $170 which was a little pricy for me, this one was $49.99. Only place to get it so far is on Ebay.
I've had it for a few weeks now and it is working great!! The only down side is the directions (or lack of) on how to install it. It came with what looked like a hand drawn sketch, a bag of hardware and the two main pieces. Didn't take me too long to figure it out though.
Works great! I did have to give up my Spin Carbon wheels though

that was the toughest part!