[Roadsters] quirky supercharger set-up picture, R-16 option?

[O'Farrell, Fergus P (AS)]

Along the lines of "another quirky thing to do to a small engine, anyone
recognize the supercharger on this VW engine?  ( roots type, I think
they call it, intake charge definitely not cooled)

http://cncpics.com/v/090905/20090912/DSC02229.JPG.html

Tiny 1 bl carb sitting on top, and looks like single port intake
manifold.  When the race reg people - see previous pics of car - stated
"stock carb req'd", I bet they never thought anyone would try to
pressurize a stock carb.

Just more ruminations,
Fergus O