(FYI: Within five minutes of posting you can Edit your post without accruing an edit notation. Just use the button in the lower right.) But hey, three replies.
An aircraft pitot tube is about a foot long to pierce through the laminar flow and best practice is to place it at a stagnation point. On a car that would be the nose.
I don't know the velocities involved in the intake system. A tube smaller than the throat might make measurement difficult, else a bellmouth could gather more air.