I've used Peters inserts off and on for the last few years with pretty good increases in low end power and mileage. They actually do something and that something is channel all the air flow directly to the jet and keep it from creating turbulence on the back side of the barrel. This is much more "innovative" IMO. A longer venturi will straighten the air flow slightly if the venturi was too short to begin with, but I cant see how it would increase mileage unless the LSN tune is off to begin with. I'm diggin the reference to jet development though I guess all venturi's can be referenced to jet research now since they are all just tapered cylinders?

http://tkocompetitiondev.com/index.php?cPath=38_51

The claim of making more HP and increasing airflow I dont buy into