It is called a venturi, and yes, it is one of the more efficient ways to streamline flow and achieve more flow with less pressure loss. Very little benefit ,if any (in performance, not looks), could be obtained by using it on a car's intake. The more important thing is less restrictive ducting to the intake manifold. i.e. bigger diameter or straiter runs.
What is this intake thing called?
What is this intake thing called?
Linear Mode
