Before everyone gets themselves in an uproar -- I'm just messin' with ya. I'm not gonna roll anyone over.

Hi & greetings I'm from Singapore!!
I have a trek 4300 '03 which weights around 29 lbs wich I bought for S$645/. Point is If I up-grade the bike to at least 25 lbs, that would literally change the entire set-up except the frame and will cost an additional S$ 1,500/. So I guess that theres no point in the whole excercise of shedding pound from heavy entry level stocks at all.

Another thing,....whats your feedback on the Continental Twister Supersonic tires??

Lastly, I have an old Schwinn S20 Carbon Monocoque full-sus bike currently weighing around 27.5 lbs. My Fork is a RS Judy XC '98 and a RS deluxe rear supension. Fork definitely will subtract. However, the rear suspension is frankly, something I don't know anything about and what to replace it with. The Rear suspension is set-up vertically and not diagonally or horizontally and rests on what they call the sweet spot pivot. Eyelet to eyelet distance is approx. 140mm. Any advise??

There is a difference between carrying 2 pounds in the bike or in the back, the total weight is the same but it is more easy to move the bike in the curves of a single track if the bike has lower weight.
Ask to a Descender.