I have found that the wiggle in the Kaos and the Kwik Fli was related to the design of the rudder pushrod and the poor servos we used tp use. Most people made their pushrods with a long 2-56 rod exiting the fuselage and then having a bend in it before it attaches to the rudder. If you re-engineer the pushrod using a 5/32" or 3/16" carbon tube with short straight metal rods at each end (preferably 4-40 at the rear) and NO bends, and upgrade to a high quality servo with a minimum of 60-100 oz of torque you will be amazed at the improvement in the way these airplanes fly and respond to rudder inputs.
Scott