Abbeysdad:
I'm using 3:1, Water:KSG - with the WOWO method.
I meant to use distilled water and ended up inadvertently using a bottled water product instead. I was concerned that using the bottled water instead of distilled water might cause some problems. However, I had already mixed up 24 oz.s of homebrew (18 oz. water/6 oz KSG) using the bottled water and didn't want to waste the 6 oz.s of SG, so I figured I'd go ahead and give it a shot and see what happened.
I've used my homebrew approximately 3 times after weekly washings over the course of more than a month and it has worked great - slickness/gloss/shine all are as good or better than Sonus AG.
I simply spray on one panel/portion of a panel, apply the product evenly over the panel with a shorter nap MF, then immediately do a final wipe/dry/buff with a different - thick/plush nap MF. If I notice that I let a little of the spray dry in an area without buffing, I just hit it with a quick spray of Sonus AS and wipe off. After one set of short nap/long nap MFs become saturated using WOWO, I switch to a second set.
I don't know what the dilution ratio of Sonus AG is, but the 3:1 KSG homebrew seems to work very similarly to Sonus AG in both application/removal and appearance/protection.