These two dyno charts show a comparison between a 1000 cfm 4150 HP Holley carb with downleg boosters and an 1150 cfm Holley Dominator carb. The engine is a 427 Sideoiler with a set of street/strip ported Edelbrock heads, a street roller cam, and 10.5:1 static compression. The upper graph shows this engine fitted with the Edelbrock Performer RPM intake manifold, and the lower graphs shows the engine fitted with the Edelbrock Victor intake. With both manifolds, but particularly with the Performer RPM dual plane manifold, the Dominator carb gives better performance at the upper end of the RPM range, but the 4150 carb works better at the lower speeds.
The peak airflow requirements for this engine were only around 800 cfm, but from the charts it can be seen that the larger carb still provides a substantial peak horsepower advantage. The larger carb offers less restriction to airflow at the higher engine speeds, resulting in less vacuum in the intake manifold and better cylinder filling.