I dissagree with the comment that differential does not do anything. It improved the response greatly on three that I built and flew. If using ailerons, take out all of the dihedral if possible and do enlarge the rudder for improved performance. IMHO this is a great flying plane once trimmed out. It is real easy to get a warp in the wing when shrinking the covering and that will make trimming nearly impossible so take care there. On the third one I built, I sheeted the wing in front of the main spar (made a D leading edge structure) to keep the wing from warping so easily.