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      10-26-2012, 12:53 PM   #29
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Originally Posted by MikeE92M3 View Post
I used a formula that I had seen on another thread for a different car (350z) Formula is V/WV (Velocity/Wavelength) standard.

V=1187 Ft/Sec for soundwaves (standard wavelength speed)

You have to find out what frequency (Hz) your drone is prevalent at. I measured anywhere from 160-180 hz, depending on what gear, in my car. So Lets say 165-175 Average. I will do 175 for the purpose of this solution.

1187(wavelength)/175 (hz, drone frequency) = 6.78

Take 6.78, divide it by 4 (conversion) (6.78/4) and you have 1.69 feet (14 inches)

The pipe needs to be at least 14 inches to cancel out the drone.

Hope this makes sense. It took me a few minutes to grasp it but once you measure the drone frequency with a microphone or app (I used a HZ app on my iphone), it is easy to do the math from there.
This is amazing information and hell of a job.