Chat,
  I had the same problem with my ES, though my baffling is different for my Lycoming installation.  I have a sloped piece up front behind the intake scoop and had an intake flange mounted on that.    What I recently did was enlarge the flange and hose to the heat muff to 2 1/4" (this requires a larger intake port on the heat muff) and I also made a fiberglass scoop that grabs the air and forces it into the intake flange.  (I've also seen scoops made from aluminum.)  The difference in airflow coming out of the heat vents was significant.  I haven't had  a chance to fly a high altitude trip in really cold air to see how the cabin warms up, but it should be better than it was.  My back seat pax had fog coming out of their mouths when they were talking before I did the mod.
  Good luck,
  Skip Slater