This question is directed at those of you who own or have owned a convertible. On some roadster convertibles. ie. S2000 there is a rear wind deflector behind and or between the seats on the rear deck. It can be flipped up when desired. How effective is this item and why not on the Solstice? I did not see it in the dealer options' list. Do the cowlings (think thats what those head bumps are called) provide a similar function? Thanks in advance for your thoughts.