I removed it because I had to replace the gas tank with one with a pressure sensor to satisfy the HX ecu. The HX-EX tank has a different filler tube so i had to change it as well- the tube and tank and sensors are functionally an assembly. The only difference between the HX/EX and CX/DX filler tubes is an added vent tube that hold a couple fluid oz. So I measured the capacity of the DX tube since it was sitting there.
It hold 3.5 cups. 1 cup = .0625 gal. so the filler tube holds approx .22 gallons of fuel. On my car that means 8.8 miles of fuel at 40 mpg. Not as much as I thought was in there.