It all depends what textbooks you read. All of my textbooks tell me that if I reduce the pressure loss of the flow through the carburetors the volumetric efficiency and the horsepower will increase. If the carburetor "rating" is 500 CFM at 28" of water pressure loss, the engine is losing about 7% or more (9% in the example I worked out above) of its potential power if the rpm and displacement are asking for 500 cfm. In the jet aircraft business, inlets are oftened designed to cause no more 1 to 2% pressure loss at max airflow.
Just keep making the holes bigger until you don't go any faster.
