I'm trying every trick in the book to help my box get out of it's own way, and am thinking about running a Braille/Deka or Odessey lightweight battery as 20lbs. of weight extracted from the Xb has gotta help. I'm just wondering if it will keep up with my sound system. It's not over the top but I've got a Sony amp rated at about 400w rms. Here's a link from a VW board with pics. I'm thinking about the 15lb Deka model.

http://forums.vwvortex.com/zerothread?id=2353060&page=1