I used the AG double in-line water filtration system today and I'm a believer. First of all, maybe its my imagination but with my foam gun, using the same ratio as always (2 oz DP Extreme : 6 oz water), I was able to take the mixing valve down a notch and got even MORE thick foam. Drying was MUCH easier and in fact, my Cobra WW seemed to work like when they were new. No water spots at all. One suggestion I might make is to use a double outlet valve on the faucet with another hose so you don't have to use and/or waste filtered water when washing out your supplies. Worth the investment if you got the $$.