There are certain chemicals that benefit from an acidic pH, glyphosate is NOT one of them.  The best adjuvants for glyphosate, and the ones recommended on the label are AMS at 8-17 lbs/100 gal and a good surfactant at 1-2 pts/100 gal, anything else might help, but not as much as AMS and surfactant.  Assert (for mustard control in sunflower) and dimethoate insecticide are two that need low pH.  We use hydrochloric acid, and it doesn't need much, maybe a qt to 1200 gallons.