Surprised no one listed the Battery. So many super lightweight choices out there. Voltphreaks 5 lb batteries to Braille 9-11 lb batteries if memory serves. Thats a good bit of weight to lose epecially for track rats. You take out the stuff DD listed at 50lbs[mats, tools spare etc] and replace the battery with a lightweight one that almost 100lbs less before you even replace the seats, rotors, suspension etc. Just my laymans 2c..Love road racing more that 1/4 mile but have yet to cut my teeth at it at any real track.
http://voltphreaks.com/
http://braillebattery.com/
A list of the Voltphreaks vs other batteries
https://p10.secure.hostingprod.com/@...ison_chart.htm