aero drag questions

If you want to release the air from under the car and out the rear bumper, Summit Racing Sells a kit to install vents in your rear bumper. You do have to cut out some of your rear bumper to install these vents. Or you can create your own custom cut out in your rear bumper. Doing this releases the air from building up inside the rear bumper. Which in turn helps the car ride faster. I did it to my own bumper.