I give up. I'm finally going to add a large CSP-legal rear spoiler on my 2006 MX-5. The small factory "Appearance Package" lip spoiler does nothing for adding downforce, and it's likely only minimally helpful on reducing drag at autocross speeds (although they are spec'd on the MX-5 Cup cars).
Several have been done on the NC - Victor Livengood and Ron Bauer, to name a few. But I still have the small factory spoiler attached.
So, Bill (actor) and others...can you give me your thoughts on if the small OEM rear lip spoiler must be removed if I add the larger CSP-size spoiler? The 2011 rules use the word "either"...in my case, I'm wondering if that can also mean "both." I'd be using the (a) rear spoiler as the attachment point for the (b) spoiler:
15.2.I.2. A spoiler may be added to the rear of the car provided it complies with either of the following:
a) It is a production rear spoiler which is standard or optional equipment of a U.S. model of the vehicle, or an exact replica in an alternate material.
b) It is a non-production rear spoiler which is mounted to the rearmost portion of the rear hatch, deck, or trunk lid. The spoiler may extend no more than 10 inches from the original bodywork in any direction. Alternatively, in a hatchback, the spoiler may be mounted to the rear hatch lid at or near the top of the hatch; in such a configuration the spoiler may extend no more than 4 inches from the original bodywork in any direction. The spoiler may be no wider than the bodywork, and it shall not protrude beyond the overall perimeter of the bodywork as viewed from above. The use of endplates is prohibited. Angle of attack is free. The spoiler may not function as a wing.
What say ye, oh gods of *SP?