You would get rid of the 300 restrictor and install one that is made for 150gpd membranes. I guess you could do it your way but the second restrictor would have to be adjustable and you would have to fine tune it to the output ratio you are seeking.Thanks for this! I have a question on the flow restrictor. If I can keep using the RO buddy it has a built in 300 flow restrictor. Should I add an additional flow restrictor at the membrane to get an added total of whatever number is recommended for the membrane size?