Another thing to look at (if its adjustable)....

Sometimes you create less drag shimming the horiz stab than the wing. does the fuselage look lkie its flying straight with the airplane's flight path... or like the nose of the fuselage is up just a bit? If the fuselage looks like its level, then try to shim the tailplane if possible. (1/2 as much as the main wing... it has more effect because the chord is smaller... thus the same thickness makes a bigger angle change)