rcdivot,

I beleive they call for extension wires because the servo wires do not normally reach to the end of the wing tubes. In my Something Extra, I did use extensions, but at the receiver end because the servo leads did reach to the end of the wing tube and more. I would feed the leads through the fuse as I attach the wings, then make the final connections inside the fuse. If you are going with a y-harness, make sure your servo arms are mounted on opposite sides of the aileron servos so you will get opposite action and not flapping action.

Good luck.