I have a couple mods that can go to 6 volts, when would use that much voltage as far as tanks, cartos,etc? I know that the hr can require higher voltage, what high resistance ohms would require 6 volts. The highest ohms in tanks,cartos,attys that I have are 2.8 ohms and 4-4.2 is about as high as I go before I taste "burnt"!! Please enlighten me and what are the upsides to hr tanks and high voltage!??