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      12-11-2012, 11:05 AM   #44
MikeE92M3's Avatar

Drives: 08 E92 M3
Join Date: May 2012
Location: Richmond, VA

iTrader: (5)

Originally Posted by m3an View Post
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.
2008 (07/08) E92 M3 BPM Stage II Tuned by Mike Benvo, 6MT, Turner Test Pipes, Magnaflow Custom Catback Exhaust (Magnaflow X Pipe, secondary cat delete, Aero Resonators and Helmholtz Chambers),Vorsteiner CF Lip, Hamann Style CF rear diffuser, CF Rear Decklid Spoiler, BMW Performance Kidney Grills, CF Side Grills, OEM GTS Wheels, K&N Drop-In Filter, GP Thunder 8k Angel Eyes, Painted Reflectors.