DA hollowtech cranks are probably the lightest readily availably cranks. You can easily get carbon stems and posts, and if you can live with it, carbon road bars. Easton track bars, if you want to $pend. eggbeater ti, 2t1, or wahtever. tubular wheels and tires will save you a bunch of weight. Carbon saddle - take your pick. All that and a decent aluminum frame will get you light, and for less than a carbon track frame.