Originally Posted by m3an
I believe those bottle type resonators are 12". But you're missing the point. You need to calculate the length of pipe needed to determine what length Will cancel out the drone frequency. Just adding the resonators alone may help but you're just guessing at this point. Some people experiment with a slide made of two pipes over one another with a clamp so you can drive around, mark the location that's right and then weld Em up. Good luck.
+1, I drove around with a frequency meter for several minutes before getting a comfortable reading to correlate where the drone was coming from. I used this frequency (Hz) in the formula and worked it out from there. After 700 miles on the "new" exhaust, drone is virtually nonexistent.
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