Unusual Carb Modification

[A383Wing]

Was talking to a long time friend of mine today about my dual quad 383 motor...I'm running a pair of 625 carbs with non-progressive linkage. He told me of a modification that someone makes that turns the carb into approximately 500 cfm by putting pieces over the primary venturi's so it makes less air go through. He says they supply the venturi slide-on barrels and jets to do this conversion

anyone heard of this?