or see if theres extra metal that you could completely cut off, or spare parts which could be smaller

you could also try drilling holes in the battery... that'll lose ya some weight alot faster. While your at it the compressor could use to shave a few pounds. :D Anyone got the pics that were posted last year of this?

Actually sprockets are a good source of weight loss depending on size. Replace some extruded aluminum (if your using it) with angle or box to save weight as well, then speed drill for even more weight loss (although its not much). Other than that make a list of what you need most and what you can afford to lose.