This product isn't an additive like a fuel additive, it is a piece of metal shaped almost like an airplane propeller that you insert in the air intake tube. It is supposed to spin the air as it enters, speeding it up and reducing turbulance making for smoother air delivery with higher volume and force. I haven't tried it, but it looks interesting.

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Jason Priest
1999 E430
1995 E420 - retired
1986 420SEL - retired