Completely eliminated exhaust drone

LX Dave

Active Member
Jul 2, 2017
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Well, in my Mustang, the drone was so bad, it was driving me nuts. When I had 3.73 gears, it droned at about 60 mph. When I went to 3.31 gears, it moved up to around 75 mph. It was bad enough that after 15-20 minutes, I wanted out, even worse with the windows up. For note, my drone was between 1900 and about 2300 rpms. While searching for a solution, I came upon this thread on another site: https://www.corral.net/threads/exhaust-drone-is-completely-gone.496793/
After reading almost half of it, I decided it's cheap and easy enough to give it a try. Over the past winter, I collected the parts I needed and went to town.
Did some measuring and decided where I would put the extra tubes and mocked one side up.
exhaust1.jpg

After welding
exhaust4.jpg

Decided to use a slip joint after the elbow so if the pipe needed to be shortened, I wouldn't have to cut the other end and keep welding caps on.
Under the car
exhaust2.jpg
exhaust3.jpg

For the caps, I found some expansion plugs that fit snug in the pipe and just tacked them in.

If you're still reading and interested, these are 1/4 wave resonators. The reason these work is when the sound waves travel down the tube, reflect off the end cap, and re-enter the main pipe, the sound wave is 180 degrees out of phase, cancelling out the noise.

When doing this, I was really hoping I wasn't cutting holes in my exhaust for nothing, thinking "it works for everybody else, but it won't for me".

After all the waiting, I finally got to take the car out for a run. Not only is my drone completely gone, but now you can barely even hear the exhaust inside the car at 75 mph now. I can now listen to the radio on trips, or actually have a conversation inside now. Before doing this, I went from Borla Pro XS mufflers to the DynoMax Super Turbos. I've heard good things about them, but unfortunately they didn't do a thing for drone.

So, instead of changing mufflers you like trying to find something that won't drone, put a set of these resonators on and be done with it. There is a ton of info in the posted thread to figure out how to tune them. I got really lucky the first time on the length of the tubes as it was perfect. The second best part, with the car on the ground, you can't see any part of these. Sorry, I don't have any pictures of it completely done (thought I did), so if you want to see more, let me know and I'll get some.
 
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Rdub6

So while I wait to figure out my rear end issues
Dec 29, 2017
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Well, in my Mustang, the drone was so bad, it was driving me nuts. When I had 3.73 gears, it droned at about 60 mph. When I went to 3.31 gears, it moved up to around 75 mph. It was bad enough that after 15-20 minutes, I wanted out, even worse with the windows up. For note, my drone was between 1900 and about 2300 rpms. While searching for a solution, I came upon this thread on another site: https://www.corral.net/threads/exhaust-drone-is-completely-gone.496793/
After reading almost half of it, I decided it's cheap and easy enough to give it a try. Over the past winter, I collected the parts I needed and went to town.
Did some measuring and decided where I would put the extra tubes and mocked one side up.
exhaust1.jpg

After welding
exhaust4.jpg

Decided to use a slip joint after the elbow so if the pipe needed to be shortened, I wouldn't have to cut the other end and keep welding caps on.
Under the car
exhaust2.jpg
exhaust3.jpg

For the caps, I found some expansion plugs that fit snug in the pipe and just tacked them in.

If you're still reading and interested, these are 1/4 wave resonators. The reason these work is when the sound waves travel down the tube, reflect off the end cap, and re-enter the main pipe, the sound wave is 180 degrees out of phase, cancelling out the noise.

When doing this, I was really hoping I wasn't cutting holes in my exhaust for nothing, thinking "it works for everybody else, but it won't for me".

After all the waiting, I finally got to take the car out for a run. Not only is my drone completely gone, but now you can barely even hear the exhaust inside the car at 75 mph now. I can now listen to the radio on trips, or actually have a conversation inside now. Before doing this, I went from Borla Pro XS mufflers to the DynoMax Super Turbos. I've heard good things about them, but unfortunately they didn't do a thing for drone.

So, instead of changing mufflers you like trying to find something that won't drone, put a set of these resonators on and be done with it. There is a ton of info in the posted thread to figure out how to tune them. I got really lucky the first time on the length of the tubes as it was perfect. The second best part, with the car on the ground, you can't see any part of these. Sorry, I don't have any pictures of it completely done (thought I did), so if you want to see more, let me know and I'll get some.
How does it sound sitting at idle, compared to before? I’d like to see a pic of the completed install!
 

LX Dave

Active Member
Jul 2, 2017
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The sound at idle and even running some rpms is close to what it was, maybe a touch deeper. I'll try to remember to get some better pictures tomorrow.
 
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Trogdor

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Aug 30, 2018
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I remember the urban legend back in the 90s the solution was to use a 2 chamber Flowmaster on one side and a 3 chamber Flowmaster on the other. Never met anyone who had tried it.
 

Essn95

Advanced Member
Jun 21, 2017
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A cool addition would be to have an electronic cut-out that opens to this pipe when at "drone-prone" speeds. Then you can have it routed normally for around town driving when you want to hear the exhaust.
 

LX Dave

Active Member
Jul 2, 2017
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exhaust5.jpg
exhaust6.jpg
exhaust7.jpg


Here's the other pictures I said I'd post. Both sides are done.
The thing about doing this, the tubes only cancel out the drone at the rpm they are tuned for. Normal driving around, the car sounds the same as it did before.
 
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7991LXnSHO

10 Year Member
Sep 1, 2010
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That looks like too much pipe to hang just with a band clamp beyond testing. I am wondering which will be better 1. a spacer between the short pipe and the intermediary pipe with a clamp around both, or 2. A universal hanger that mounts to the body (used to be frame) and a standard exhaust clamp.
 

LX Dave

Active Member
Jul 2, 2017
170
96
38
46
That looks like too much pipe to hang just with a band clamp beyond testing. I am wondering which will be better 1. a spacer between the short pipe and the intermediary pipe with a clamp around both, or 2. A universal hanger that mounts to the body (used to be frame) and a standard exhaust clamp.
I've been thinking about doing something to support them towards the ends, but not sure what to do yet. They are extremely rigid as is right now, so not in a big hurry to do this. I did put in a self tapping screw so they can't walk out. I could probably attach a bracket to the seat support of the sub frame connectors, then to the pipe. Have to look at that again.
 
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KRUISR

5 Year Member
Apr 16, 2015
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Run a short piece of 1/4 or 3/8 rod over from the main exhaust pipes. Basically make a shelf that is welded to the main exhaust and your resonator pipe can rest on.
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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polk county florida
Then how would we know that the anti-drone pipes worked?
They could be marketed as a kit, :chin
No Drone Kit
Simple, adjustable kit so you could cruise in the 'No Drone Zone'.
Get your 'No Drone' kit now while supplies last!!
obligatory legal notice
WARNING: this product is intended for use in automotive applications only, attaching pipe to rectum has caused cancer in laboratory rats but only in California.
 
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LX Dave

Active Member
Jul 2, 2017
170
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Then how would we know that the anti-drone pipes worked?
They could be marketed as a kit, :chin
No Drone Kit
Simple, adjustable kit so you could cruise in the 'No Drone Zone'.
Get your 'No Drone' kit now while supplies last!!
obligatory legal notice
WARNING: this product is intended for use in automotive applications only, attaching pipe to rectum has caused cancer in laboratory rats but only in California.
Ya know, warnings are usually put on something because somebody just HAD to try it...just sayin'.


I put a set of the Borla Pro XS mufflers on this one because I liked the way they sounded on my '87. On this car, they droned really bad, on the '87, almost none, but that one has cats. Doing research, a lot of people were saying the DynoMax Super Turbo mufflers cut the drone quite a bit, so I picked up a pair of them. They didn't help in the least bit. I didn't want to keep spending $1-200 and an afternoon every time it didn't work, and I have no need for cats on this one. This was the much cheaper route, and I get to keep the sound I like. The Turbo mufflers do sound good. The only time the resonators really quiet it down is cruising in the 1900-2300 rpm range (around 75 mph with the gears and tire size I have). At any other rpms, there was no drone.
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
19,904
6,698
193
polk county florida
Just imagine the guy that has to stick that pipe to a rats azz, the whole time he's mumbling ' come on out to California, you can get a job, it'll be fun' he says in his best John McClain voice