Keep in mind if you go to a SID you will lose at least an inch of travel. They are supposed to be 80 mm but most people get close to 70 mm out of them.
What wheelset do you have now?
If you want to lose some weight replace the bottom bracket with an American Classic Stainless Steel. You will lose close to a 1/4 pound with just that change. After that a carbon bar and seatpost would be nice, also check out some egg beater pedals to save some weight. Depending on your riding you could also go with some lighter tires to save some weight for minimal money.
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I may be fat but I'm slow enough to make up for it.