I estimate that for my 1.8 liter engine (2006 Civic) I needed 0.5 to 0.8 lpm HHO output to feel the boost. I combined this with air constriction after the MAF sensor to get 45+ MPG highway.
Once I install this on my new 2012 Kia Rio SX (just sold this Civic lately) I will get a video of the amp draw.
I also found late 2009 that replacing the cathode with Nickel Alloy (Monel 400) pushes efficiency higher. This design is similar to LENR devices built by Andrea Rossi. Check him out.
Just sharing.