I found a solution for the slow head sink drain that many of us have complained about. I installed a 3/4″ 90 degree barbed fitting directly below the sink drain tailpiece. I then connected a piece of hose, curving in the longest arc I could fit in the available space, between the fitting and the thru-hull. This curve provides an escape for the air bubble that used to become trapped when the hose was vertical. Just make sure the hose is angled downward from the start or you could create another opportunity for an air bubble. Now the sink drains very nicely even when I’m using high pressure city water.