Front chin spoiler

A chin spoiler will serve one or two purposes depending on where you mount it. If you mount if under the rad support, it will force air up and into the radiator. If you mount it under the bumper it will help prevent air from going under the car.

With all that said you can (depending on your fab skills) make a combo of the two. You mount it under the bumper but have a fabbed section in the center that bolts under the radiator that has a recess/tunnel that will divert air to the radiator. Boom now you prevent excess air getting under the car but also air in the cooling of it. Best of both worlds the post above gives a great picture of what I'm talking about but you adjust it to fit your needs/preference