I have a TGI-315. It's basicly 2 filters and membrane. The water was tasting a little funky so I decided to change all 3. I also replaced my auto shut-off valve because I kept dumping water down the drain. I've had a RO system for about 10 years and have changed the filter many times. I noticed that the water seemed to run out real quick. I checked the storage tank and it seemed very light. I checked my connections against the schematic and everything was good. I pulled the filters and made sure they were not plugged or the rubber seats hadn't moved. After restarting the system I couldn't build up enough pressure to fill the tank at all. It's like there's another blockage now. I put the water on and checked fitting by fitting: I'm not saying I knew where it stood prior to this but there seemed to be a "big" pressure drop across the 1st stage filter. The system seems pretty simple according to the schematic. The only thing I haven't changed is the restrictor, but I did pull it out and clean the screen (it didn't seem dirty, but I figured what the heck). I also noticed that I had good flow without the restrictor in the system which makes me lean that way. Any ideas would be very welcome.