Hi All, I only have a 450GPD unit at the moment and to be honest it suits my needs for now, I was thinking about upgrading to a 40/40RO but upon reflection the only thing I would save is time filling the tank. So Ive decided to stick with the 450GPD unit for now. I want to upgrade my DI vessel to a larger on as I have to constantly change the resin in my SMALL 1Ltr cartridge. I was thinking of purchasing an 11ltr one?? Is it as simple as I think? remove old 1Ltr housing - secure new 11Ltr vessel - connect existing hose and *Boom* all done? Not sure about when it comes to water pressure's ect ect??