Yes that is true, but why would you want 8:1? your just wasting a lot of water and also throws off the pressures the units needs to function correctly. The flow restrictor that was installed was put there for that membraine. Don't mess with it, just use the unit like it was intended. Get another flow restrictor , put it in and leave it alone, you will be ok. I think you might be trying re-engineer the unit and it don't need that. Measure the TDS at 8 to one then adjust it between 3 to 5 to 1 and measure again, you will see a much lower TDS because an RO membraine needs a min of 40psi to work. So if you open up the drain line all the way the pressure inside the membraine drops. Your basicily bypassing it. Thats the best way I can explain it, which as I hope you can now see thats why you have had so much trouble with the unit. If you have the correct restrictor and you keep your filters changed ofter there is no reason why the membraine won't last 3 or more years. Remember I have been thru 3 membraines because of this, so I know what I'm talkin about.