..using the 55w bulbs.

Its seems were loosing voltage too, which may be somewhat expected.

High Beam Votage:

With both the H & L beams powered I disconnected both H beam bulbs and got a reading off

13.64v w/ Both bulbs off.
12.86v w/ one bulb connected
12.78v w/ both connected.

Low Beam Voltage:

With both H & L bulbs disconnected on both sides I got a nice reading of 13.54v.

13.19v w/ Both H disconnected and 1 L connected
12.96v w/ Both H diconnected and both L connected
12.80v w/ Both L connected and 1 H connected
12.51v w/ them all connected.

12.51 is fairly low for a 55w bulb IMO. Seems to be a good idea.