Hood scoops are designed to suck in cool air during vehicle operation and feed it directly to your engine. To accomplish this, the placement of the hood scoop and its design are critical. A hood scoop must be in a high-pressure zone on your hood. For this reason, many vehicles have their hood scoops located near the cowl of the hood where the curvature of the windshield creates a high-pressure zone for air.
Through a small inlet, a functional hood scoop sucks in air at a higher pressure allowing it to feed more air to your engine. A tight connection to the air intake manifold must be sealed and allow for the shortest pathway possible for air to reach your engine. This effectively forces your engine to breathe all its air through the scoop while driving. Considering the air being sucked through the scoop is cooler than the air located outside of your cramped engine block, this allows for greater combustion and thus improved power.
Hood scoops effectively act as a cold air intake system. Cold air intake systems are also compatible with hood scoops that use a forced induction system, allowing for the same cold airflow when idling or driving at slow speeds. It’s important the scoop tube or channel is insulated from engine bay heat. A poorly designed hood scoop could be more detrimental to your Mustang’s performance than choosing not to purchase one.
There are also non-functional hood scoops or closed hood scoop systems which are purely for aesthetic design. These are more aerodynamic than an open hood scoop, still adding to your Mustang’s fuel economy.
On the other hand, there are hood vents that allow your engine to release heat generated from the engine bay. These also improve performance, but don't offer the same capabilities a hood scoop does. Many factory Mustang models already feature hood vents, and replacing a heat extractor is cheap. Of course, for total performance, a hood scoop near the cowl will offer your engine greater performance capabilities and increase its life.