If your hopper really is the Extreme Rage version, (ie. the current version that doesn't
say "Sportshot" in gray writing on the side) it already has the "sanding" mods incorporated into its design from the factory.
Even with modifications, small non-motorized hoppers just don't feed that consistently. No amount of modification or sanding is going to prevent you from having to shake the hopper once in a while.
Anyway, Pumpenstein's old article can be found here, though most of the images no longer work: http://www.mcarterbrown.com/forums/d...ed-better.html