Snake oil! If these really were such a great investment, certainly some of the big auto manufacturers like BMW, GM, Ford, Mercedes, Porsche, etc. would use them (or a similar device) in their products. Save your money! And if its burning a hole in your pocket, you might want to consider this fancy air cleaner from: http://www.alsblowers.com/streetinduction.html
I'm sure you would get similar power gains.
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