RE: Welcome to Club SAITO !
Hello; It is my understanding that the velocity stack on the carb is to contain the fog of mixture that is blown out the carb when the valve closes. It keeps the fog available for when the valve opens again. Without the stack, the fog will just be blown away and stick to your firewall, or otherwise not go into the engine. This will take advantage of fuel that you would otherwise lose.
Saito is right in saying that the velocity stack isn't needed, but it's a good idea for economy, and it will keep your firewall cleaner.