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2Addicts | BMW 2-Series forum Technical Topics N55 (M235i) Engine, Transmission, Exhaust, Tuning Exhaust comparison with digital sound level meter

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      01-07-2018, 01:28 AM   #1
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Exhaust comparison with digital sound level meter

Hey everyone!

I was trying to make a decision on whether or not to get an exhaust bypass (Muffler delete) and could not find any good videos with a good mic and real testing on sound levels during my research period. Just a bunch of people saying it was loud or not that loud or super loud and everything in between!

I finally went out and picked up a Rode video mic along with a sound meter to really document what kind of sound you'll get so you can get a fair and decent comparison to help you in your decision making.

First video is with M Performance exhaust, stock everything else. Second vid is Fabspeed bypass, stock everything else.

With the MP Exhaust, cold starts topped out at about 82 dBa and revs topped out at 92.4 dBa.

With the fabspeed, cold starts topped out at about 98 dBa and revs topped out at 103.8!!!!

A difference of 16 dBa cold start and 11.4 dBa difference in revs. Keep in mind that every increase of 3 dB represents a doubling of sound intensisty (acoustic power).





Hope this is able to help many more people that will reach this cross road eventually. And yes, if you are asking me, it drones.

Last edited by Bmw.Fan; 01-08-2018 at 10:08 PM..
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      01-07-2018, 03:50 PM   #2
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Good stuff, thanks.
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      01-08-2018, 11:51 AM   #3
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Thanks for testing and sharing!

I noticed that the angle is much lower (in direct shot of the exhaust) in the second video, so could that have affected the decibel reading? What was the distance for each?
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      01-08-2018, 12:05 PM   #4
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Quote:
Originally Posted by cxp213 View Post
Thanks for testing and sharing!

I noticed that the angle is much lower (in direct shot of the exhaust) in the second video, so could that have affected the decibel reading? What was the distance for each?
The distance was measured at 8ft 4 inches each time we did the test. The height should not have a large impact at 8ft length.
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      01-08-2018, 05:06 PM   #5
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Interesting thread, thank you
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      01-09-2018, 09:33 AM   #6
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Quote:
Originally Posted by uisynot View Post
The distance was measured at 8ft 4 inches each time we did the test. The height should not have a large impact at 8ft length.
I guess that exhaust is that much louder. Thanks again for sharing.
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      01-09-2018, 11:11 AM   #7
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Thanks for the test. I have a FabSpeed Sport exhaust. To me that thing is perfect. Not too loud and no drone.
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