If you have access to a unit to 'try', do yourself a favor. I never believed in it either until Tom let me borrow his SB over the winter since his car was going into storage. I knew it made a difference, but once it was removed, I was shocked how flat the car felt (his was not adjustable). Now that I have the adjustable one, you can turn it off, medium, or race, and every time I turn it off I am reaffirmed in the great decision I made to purchase.

While it is no HP, the gain in responsiveness is so impressive it makes you wonder how Benz got it so wrong. It will definitely improve the feel of the car more than diffusers or side skirts