It isn't the carbs that kill off the power in a six pack setup it is the twists and turns inside of the stock intake. The porting helps and with a smaller cam like JBC has the numbers are close. In a street engine the dual plane design really helps with the low end torque. Flip over to a race engine and the dual plane kills off the high end power.
The NHRA super stock guys run the Holley carbs (required by rules) but they use custom sheet metal intakes. Those engines wind to the moon and make a ton of power. So it isn't the carbs, it is the manifold. And the manifold is just fine for street use.
This..^^^^, in a big way Iagree. The small block intake has tall stands for the carbs and creates a deep deep long drop to the bottom plane. There's sharp turns there. Also, you can see how the #1 cylinder runner is kind of a up and down slope runner, to low IMO.
Like Andy said, it is a dual plane. That itself is a limitation. Excellent for the street, street strip car. Also know that the old Direct Connection carbs flowed more than the OEM set did/does.
