RE: How did my 100cc yak come out to 30lbs?
Aeroworks weight claims are based an minimal equipment. Minimal equipment is a power system (ignition included) of 1 pound or less, like three 2600 Fromecos and regulators. The weight of a power box or extra receiver is not considered, the weight of a pilot is not considered, the weight of a choke servo is not considered, the weight of a smoke system is not considered, the weight of cans is not considered, the weight of a 3-blade CF prop is not considered. Beyond that, certain custom graphics, particularly those fancy metalic-looking ones, can add a noticeable amount of weight. If you used up an ounce of glue to beef up some joints, that adds weight. Sure it's only an ounce, but an ounce nonetheless.
27-28 pounds is the minimal equipment, allowing fudge factor for different weights of wood used during construction. So take that weight range and add 1.2 pounds for the cans, another 5-6 ounces for the 3-blade CF prop, and another 7 ounces for your dual 5200's and you are within that weight range.
Also, if this is a new kit, the wood might still have some water weight in it. Don't laugh - my friend lost 3/4lb on a 33% SD Yak after reweighing the plane 2 months later.
Pictures of your equipment install would be nice...