This is what I've found, too. Volume (CFM) output is more critical than pressure. Your household water pressure is almost certainly somewhere shy of 55psi. I wouldn't use more than about 40psi to blowout the sprinklers. I borrowed my brother's 20 gallon compressor last year and it was pretty marginal. I was hoping to have my big 60 gallon 220volt unit installed before this year, but it hasn't happened... Always some other project burning at my feet!