Another factor in the dilution is the strength of shampoo mix you start with. You don't (or at least *I* don't) put straight shampoo in the gun's cup, you mix it with water and *then* put it in. So it gets diluted twice.
I am *far* from scientific about it, some would say I'm downright careless

I just mix up some shampoo/water mix in an old gallon shampoo jug, entirely by eye (as in, "yeah, that looks about right") and then adjust how it comes out of the gun (again, purely by eye, judging by how the foam looks) using the sliding mix valve. And as Bill D said, I use a pretty strong mix.
Even though this is just *so* hit-or-miss sounding, I never have a problem with it compromising my LSP. Maybe my "by eye" concentration just happens to be right :nixweiss
Or maybe the shampoo I use (Griot's) is just very gentle on my LSPs. I suspect that *this* is the case, since my 6 layers of KSG lasted over a year.
In any event, the exact concentration you use doesn't seem to be a huge factor in my experience.
OI812- Love the "in action" pics

Works better without the pistol grip part, huh?