I drilled 3/4 inch holes in the four outside end ribs because this will hold the black ribbed wiring plastic hose that Van's supplies. I drilled all the middle ribs 7/8 so that I can easily run the plastic wiring hose through them later. I called Van's tech support and asked if 7/8 was okay for this hole and they said, "no problem." I used a two-steel bit at low speed (about 600 RPM) for the 7/8 hole. Works great. And I used the unibit to enlarge the pilot holes to 3/4, also at low speed. I also enlarged the lower tooling hole to 5/8 per Van's provision page for use later on more wires or whatever. The center tooling hole I left as is. This is shown as a hole for pitot tube later.
