Well Ray, here's the thing.
The how-to lists the various sizes based on the smallest hole that will keep a car at idle under cold startup. The goal that I & this young CEGer have is simply to defeat the moose & some throttle hang. You can drill out the cap with the largest diameter hole - even a little larger, and you'll still accomplish the required tasks. AND you'll also allow your IAC to control idle to a significant degree.
But WAIT, that's not all! When he contacted me I was going to ask him about his car & make the appropriate size hole for his application - according to the how-to. Woulda been fine, I thought. But you're the expert.
