Another reference I heard at a homebrew con seminar was you want your pint glass to fill in about 8-10 seconds. I keep my keezer really cold (35F) and I've iterated my way between pressure at the regulator inside my keezer, and length of 4mm ID EvaBarrier lines. It took a lot of tweaks, but I have about 6 ft of line, I don't get excess foaming, I like the carbonation level, and I fill my pint glass in about 10 seconds. I also did some strategic positioning with an air circulation fan to blow right on the long 6" shanks that stick inside the keezer collar. That has kept them within 2 degrees of the temperature at the keg midpoint level.