The Dust-Turd project.

Did that with and without the air cleaner, lost 2 mph without the air cleaner. I suspect the dirty air turbulence under the hood form no fender-wells or inner panels. Another possibility is venturi effect of air flowing over the top of the carb and out the rear of the hood. ( lightweight hood lifts up in the rear at speed, I can see the top of the carb going thru the traps, LOL).

Once I jet the carb for the airbox, It may be hard to gauge a performance diff removing the pan.
Car was running 106 in the 1/8 and 130 in the 1/4 before, I would exspect little diff in the 1/8 ( .5 mph) but 1-2 MPH in the 1/4. We should see this week.