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      11-09-2012, 05:36 AM   #1
dogbone's Avatar

Drives: '09 E90 M3 - IB
Join Date: Feb 2012
Location: 93 million miles from the Sun

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2009 BMW E92 M3  [0.00]
2009 BMW E90 M3  [0.00]
Test Pipes vs Stock Exhaust recording comparison

I went to EAS for a Macht Schnell test pipe install and decided to record the sounds of the car before and after.

The car has a VF620 kit and the exhaust was completely stock.

I don't like a loud smelly drony car. But I did want to ease the flow of air leaving the s/c'd engine, so I decided to give the Macht Schnell pipes a try. I left the rest of the exhaust system untouched.

I brought some hi-rez microphones (QTC40) to record the sounds of the car before and after the install. I've edited some of the recording takes together into a video. There's a set of sound level meters in the video to show the levels.

There are 4 recordings:
-Dyno Before. Also, the engine idling after.
-Dyno After. Also, the engine idling after.
-Engine start and slow drive away Before install.
-Engine start and slow drive away After install.

Watch the video in fullscreen and highest resolution for best results:

Conclusion: I'm happy with the results.

-Only about 4-5 decibels louder on average, which isn't much at all.
-The tone has changed a bit once you get past 3500 rpm. It's a bit more raw and raspy. I like it. Has a nice aggressiveness to it. This rasp/growl gives a bit of attitude but isn't enough to raise eyebrows. On the freeway, no authority figure will pay you any mind---at least for noise.....
-No smell change to the car.
-There's about a 20 whp and 20 ft-lbs of torque gain in the mid-upper range of 4500-7500 rpm.
-There's ABSOLUTELY no drone in the car whatsoever. At 70 mph, 2800 rpm, inside the car sounds exactly the same as when the exhaust was stock.

Today, I had 100 octane in the car. The highest run peaked at 564 whp after the pipes were installed.

Anyway, I hope these higher resolution recordings help someone else in their decision making process. iPhone recordings can be hard to interpret.

Here's a picture of the highest pre-install dyno run (run34 - 551whp), and two post-install runs (562, 564 whp).

Thanks for a good day Tom, Steve and EAS!
Attached Images