There was a discussion about late '60's Camaros and their spoiler options in Stock and Super Stock racing. Apparently the spoiler option included the front & rear together. Some were trying to run with only the front spoiler, which wasn't legal. The front spoiler was said to help aerodynamics by keeping some of the air from getting underneath while the rear ducktail spoiler was left off because it caused more drag and slowed the car a bit in a drag racing application.