Sitting here after riding home from dinner with nothing special to do, so I thought I'd figure out just how much air a 103 could possibly use. Assuming I haven't forgotten something (old-timers is getting worse all the time), this is how I figured it:
-Assumed volumetric efficiency = 100%
-Maximum RPM = 6200
-Displacement = 103 in3 / 2 = 51.5 in3 per revolution (one intake event per cylinder every 2 revolutions)
-1728 in3 = 1 ft3
51.5 in3 X 6200 RPM = 319300 in3 per minute
319300 / 1728 = 184.78 CFM
Unless one were to drastically improve the volumetric efficiency, increase the displacement, or fit a blower, extremely high flowing filters would be overkill. The regular K&N used with the SE or Ness backplates should be more than sufficient.
Jerry