I installed mine in 2016. Here were my results that I posted in a different forum.
My DC uses 5" duct, reduced to 4" at three drops, it is ducted through a Super Dust Deputy and exhausts outside. The longest run is 41', using a handheld anemometer, here are the results.
Before: the average at all three drops was 325 cfm
After: average 640 cfm. However, it does make the motor work more, using a amp clamp meter, here is what I found.
Before: Startup amps, 14.27 Running 10.17
After: Startup 18.7, Running 12.7
The only change I have made since is to add a drop for my lathe.