Ok, so I tried it with softened water form inside and made a huge difference in foam output. Now it's much more like in the videos with 4oz soap. Although, when I do rinse with the soft water, the water doesn't flood off the car like it usually would.
and noticed an immediate difference in the foam, it went from being just OK to "what I expected from a foam cannon". I mainly bought it to help with waterspots, but this is an added bonus.
I've noticed the difference, for the better, in the MTM and Gilmore foam gun, while on the filtered water.