This really is a 16 to 1 downhaul. I had one on my Tornado and it works great. To get more downhaul, you can do a couple things. The easiest: stretch the main luff rope by by downhauling to the max and then releasing it, and adjusting the blue downhaul rope to take up all the slack gained in the system. You want your downhaul initial setting to be at around the minimum downhaul setting for max depth on the sail.

The second: have a second grommet put in your sail up a little bit (six inches to a foot) from where your current grommet is. This will give you more room for downhaul adjustment. On my Tornado, there was over 2 feet between the bottom pulleys and the blocks on the sail after I had done an initital pull down on the luff of the main. I would occasionally get pretty close to max adjustment when the wind was honkin'.