SChema

iTrader: (2)

A velocity stack does what it sounds like it should. In short, it creates an acceleration effect. It's more noticeable on NA motors; the charge follows the stack as the intake valve is opened, once it closes pressure is formed at the valve. This pressure is then forced in at the next valve opening. Runners found on the intake manifold achieve the same effect using longer tubes.

On boosted applications, the charge is already pressurized so gains are minimal, if any. So yes, it's eye candy.