Mccann Industries is supposed to be quite a light stock according to it's description from the manufacturer and the defensereview post, if it's lighter than the others, I have no clue, but just thought I'd throw it out there.
http://www.gokart.net/shop-utopia/mccann/
DefRev article
http://defensereview.com/modules.php?name=News&file=article&sid=1112
http://www.gokart.net/shop-utopia/mccann/
DefRev article
http://defensereview.com/modules.php?name=News&file=article&sid=1112