Anyone Currently Using a Classic Water Injection System?

Water injection is an antidetonant and also can be used for certain types of emissions control (such as if you want to pass NOx emissions while running extremely lean AFRs). May have made sense when leaded gas had just been banned and Big Oil couldn't figure out how to put back the octane. Now, water injection really only makes sense if you're running a lot of boost (like the WWII aircraft) or for some reason trying to drive a 14:1 compression race motor on the street on pump gas.