[AG2009]

Okay, this is pretty straightforward. I had a shop install my new-to-me M5 mufflers, and while the sound has really perked up, I'm not happy with the droning that I'm seeing at highway speeds. (it's kind of a motorboat-ish low bass note) I'm stock everywhere except the M5 mufflers. In searching, I've seen people that have used a J-Pipe to mitigate the drone. If this been done successfully, what length pipe did you use? My calculations, assuming that the drone is around 1750-1800, come out that I need a 36"ish pipe. does that sound right? The other idea I've been toying with is replacing the stock resonator(s) with the Vibrant ultra-quiet. Or adding a second resonator, or a bullet style muffler. (I'm thinking part of the drone is related to the smaller capacity of the newer mufflers, but I could be totally off base...) I don't really care if adding a replacement/second resonator, or secondary smaller muffler quiets the overall sound down, since i can use my homelink button to open the valves in my mufflers at will...

-or-

if you've found a way to eliminate the drone in some other method, let me know, since I don't really want to go back to stock over what should be a simple fix.

Thanks everyone!

[lsturbointeg]

going the Vibrant resonators sounds ideal but I only heard of guys going that route after eliminating the OEM resonators so i'm not sure how much more quieter the Vibrants will be. now bmwdoubles did the J-pipes and I believe that helped with the drone

[mrderekmeier]

Hello,

I replaced the mufflers on my 535i with M5's and added a vacuum pump/purge solenoid to operate the flaps for $45. I wired these both to a 3-way momentary switch and use the same power source since only one of them needs to operate at any given time. I wired the two devices so when I press switch up it activates the vacuum pump (opening exhaust), and when I press down it opens the purge valve (releasing vacuum and closing exhaust flap). This little vacuum pump is perfect for the job! I literally only press the switch for 1-2 seconds and it opens the exhaust fully. The beauty in this is the little vacuum pump turns off the second you release the switch, but it holds the vacuum all day keeping the exhaust flap open! If I want it to be quiet for a highway trip or coming home late at night I just hit the switch down for 1/2 a second, purge solenoid opens, and exhaust flap closed.

I didn't take pics of my install, but I did take a pic of the setup I used. I hid these in an empty trunk space below and ran vacuum tubes through an existing rubber grommet and T'd outside of the car to each muffler.

Dorman-911-800-Purge Solenoid - $22
12v Vacuum Pump - $21
On-Off-On Switch - $2

[AG2009]

I'd love it to as simple as swapping out the stock resonators, I'm hoping that maybe someone has tried this and had great success. I'm even open to putting a second resonator behind the stock ones. All I need is to get rid of that drone at 1750-ish RPM

[Ngnet]

Originally Posted by AG2009

I'd love it to as simple as swapping out the stock resonators, I'm hoping that maybe someone has tried this and had great success. I'm even open to putting a second resonator behind the stock ones. All I need is to get rid of that drone at 1750-ish RPM

Have the same issue with my 535i but with performance exhaust. Subscribed,

[AG2009]

We did something similar, but using a slightly different vacuum pump. The switching is handled through a remote relay set that is programed to buttons 2&3 on my homelink visor. (at least in theory, I haven't tried since the install of the M5 mufflers) I'm just trying to figure out why these mufflers are sooo droney at 1700-1800

[MOBF10]

The drone is not bad at all with m5 mufflers on the 535i. I read so much about this before I installed mine and my conclusion is people must have not ever installed aftermarket mufflers on their cars before. You'll get drone with ANY aftermarket muffler you put on ANY car. But back to what I was getting at, the drone from the m5 mufflers is not bad at all. Sack up.

[baconbits]

Exhaust engineer here.

Simply put, the M5 muffler guts are designed for the S63, not the N55. They aren't mitigating the bad tones (we perceive as drone) because the engine isn't producing them at the same frequency, among a ton of other variables.

[ssneck]

I know the way to put M5 mufflers and avoid drone with help of electronic valve control!

Follow this link: https://f10.5post.com/forums/showthr...1#post24703201