pahsaw! It is simple to achieve near 100% efficiency with most monolithic IC regulators by the simple application of the 'Linear Parasitic Shunt' approach: 1) lift the Common (or Adjust on adjustable regulators) pin and leave that terminal floating, 2) apply the Linear Parasitic Shunt ( a short length of 1 gauge solid copper conductor) between the Vin and Vout terminals of the regulator in question, 3) remove the output ripple filter capacitor. It should be noted that some control of regulation and thermal limit shut-off capabilities will be lost, but this is a small price to pay for the greatly increased efficiency obtained. Patent pending.......