BBK 3/8 inch Phenolic Factory Intake Manifold Spacer Kit for Ford Mustang 5.0L is a great way to increase performance. It is CNC machined from a custom phenolic fiber 3/8 inch thick material. These spacer kits increase power by reducing the transfer of heat from the lower to upper intake manifold. This in-turn produces lower inlet air temperatures which results in added horsepower and the ability to add more timing advance with less detonation.