I like to take my HS 55s apart and drill lightening holes in the servo case, and in the gears. I also drill out those little steel axles that the gears rotate on . Then I acid dip the individual battery cells, because the standard cell containers are WAY too thick. You can also save some weight at the RX by removing and throwing away the case and deleting all the components on the circuit board that you don't need, like the throttle and rudder channel stuff. Of course the lightest fuel tank is NO TANK at all, just seal off and fuel proof the front end of the fuselage, then push a light weight fuel line into it, done deal.

If you are using good, light wood to begin with, lightening holes aren't a good idea. If you are using tough, heavy balsa, then you shouldn't be building a 1/2A plane with it anyway, that kind of wood should be set aside for building doll houses.