This modification came from the Gleaner board and it seems that they prefer 3" suction hose because it is more flexible than pvc pipe. Some still use the pvc pipe and cut it into several pieces for added flex.I think the modification started out in a year of wide spread short beans and aids in getting them into the auger with less bunching. Also aids in keeping loose beans from dropping off the cutter bar.Replace the guard bolt with a longer one, fasten the guard in place then use a second nut to secure a conduit clamp of the right diameter to match the hose. When I tried this, the recommended sizes and materials varied,and 3 to 3.5" seemed too big for me so i used 2" schedule 40 pvc, in one piece across the head. Clamp about every 2 feet.On an 820 head ,it doesn't change the flexibility.Works better than I thought it would so have not changed and is easy to store in the tube of the header trailer.