I am blowing out my own system. 25 gal, 5.5 hp compressor. 8 cfm at 50 psi. It is plenty to pop all heads and blow steady water out each. As the water is finishing, the heads start dropping due to only having 8 cfm and air escaping from heads once water is done. I know it is not getting every drop that a trailer based compressor would get, but my question is... at that point, when the heads have dropped and it is sputtering, have I gotten enough out to not have to worry about any freezing issues? Appreciate any feedback.