Bill Strong: The Plumley mod has been tested by Deno, Bruce, and myself. It does alter the flow of the air over the rear of the car. The stock spoiler location gets into the airflow at high speed, but barely; only the tips and the sides. The under spoiler flow increased by moving the spoiler back. Side airflow is increased as flow from the buttress is now hitting the sides of the spoiler. By removing the center support pod, you also increase the available area that can be applied to the total underwing dimensions that effect lift. I have been behind Deno while traveling at extreme high speeds. I can tell you for a fact that the airflow off of Denos car is much different than that of a stock MK1. That spoiler really does create a "hole" in the air in back.

Actually, Deno's father, Bruce, is the one that it is named after since his dad is the one who discovered some things about the spoiler after one track day event. He saw the dust on the top of the spoiler and saw how the air flow affected it. Then they moved the spoiler back and the dust went by-by.