I have a '16 F250 and the Hydrastar unit works without me having to add anything. I then Googled and found this
https://www.hydrastarusa.com/pdfs/Co...%20Revised.pdf

My only issue is about a half a second delay before the brakes activate. I am thinking of installing a small 12V battery next to the unit to see if it speeds it up. This would easier than me rewiring everything with larger wire, if that is the issue