I'm about to do a 5 gal Belgian Saison with 7.5 lbs of DME. In previous extract brews I have only boiled 2.5 gallons, and then added ~3 gal cool water to the fermenter. I was wondering if I should increase the volume of water I boil. What would be the difference if I boiled 4 gal for instance? I have a 5 gal kettle so that is my only limitation.