One of the local professional brewers here recommends using a "foam settling boil" prior to adding hops. I used this technique yesterday for a 3 gallon boil in a 5 gallon pot and did not get hardly an ounce of foam. I usually have to add a drop or two of D-150 to prevent boil-overs, but not this time. The technique for my recipe was steeping grains at 165 for 20 min, off heat, add and stir in extract, slowly raise heat till a "light" boil is reached for 5 minutes, then begin the hard boil and add the hops and begin timing. Got a vigorous boil and the surface looked like I had already added the de-foamer.
"If you don't try it this year, you'll just be another year older when you do" - Warren Miller
WARNING: Drinking may cause memory loss, or worse, memory loss.