No BS, dgman. The ratio of 4% recommended by BH is the ratio that comes out of the nozzle and onto the car, not the ratio in the bottle. That thread shows how to calculate how much to put in the bottle depending on the anufacturer's ratio, your pressure washer, your foam lance etc.
As an example, when I did the test, it showed that I need to use approx 300ml of BH Auto-foam and 219ml of water to end up with a 4% ratio coming out of the nozzle. These figures are meaningless though if you don't have exactly the same pressure washer and foam lance (and foam lance setting) as me, and the same domestic water pressure as me.
When I did the test, I had 1L of plain water in the foam lance bottle. To totally empty the bottle I put 13.45L of water through my pressure washer, so that was 14.45L of water coming out of the nozzle to the car. Therefore for 4% of Auto-foam out of the nozzle I need to use 0.578L (578ml) of Auto-foam in the bottle, since 0.578L is 4% of 14.45L.
If your supplier recommend 1-5% then do the test as per the thread link on Detailing World, and see how much product you need to put into the bottle.