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      08-19-2020, 07:36 AM   #23
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I can't believe that those with drone aren't installing a J pipe. Is there no room anywhere to put one?
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      08-19-2020, 09:01 AM   #24
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Originally Posted by cecaa850 View Post
I can't believe that those with drone aren't installing a J pipe. Is there no room anywhere to put one?
Do you know the length of the resonant soundwave to make such a thing?
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      08-19-2020, 09:21 AM   #25
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Originally Posted by Anthony1s View Post
Do you know the length of the resonant soundwave to make such a thing?

Don't trust my math but I came up with about 24 inches. There are formulas out on the web in several places. Find out the rpm that the drone is loudest and plug that in to the formula.

I had a really bad drone in my Gladiator at about 2100 rpms after I replaced the center 2 mufflers with a Magnaflow. A 32" J pipe absolutely killed it.
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      08-23-2020, 02:51 AM   #26
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I agree that my factory MPE sounded great, but that damn drone was awful. I replaced it with stock exhaust for quite cheap and the drone is gone. The magic of resonators.
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      08-23-2020, 12:01 PM   #27
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Quote:
Originally Posted by cecaa850 View Post
Quote:
Originally Posted by Anthony1s View Post
Do you know the length of the resonant soundwave to make such a thing?

Don't trust my math but I came up with about 24 inches. There are formulas out on the web in several places. Find out the rpm that the drone is loudest and plug that in to the formula.

I had a really bad drone in my Gladiator at about 2100 rpms after I replaced the center 2 mufflers with a Magnaflow. A 32" J pipe absolutely killed it.
Not sure where you can up with 24 inches. Maybe I'm looking at the wrong formula, but I got the following:

((1125) / (RPM * 6 * (1 / 60))) / 4

At 3000 RPM, that works out to 0.9375 feet, or 11.25 inches.

1125 = speed of sound in feet per second.
6 = number of pulses per revolution in a 6 cylinder engine
1/60 = convert from minutes to seconds
4 = quarter the wavelength to cancel out the resonance.

This is actually an interesting idea, I'm just curious where in the exhaust you'd be able to put it. Perhaps right before the y pipe, and have it tuck back behind the exhaust can? Might be some room there.
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      08-24-2020, 08:34 AM   #28
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Quote:
Originally Posted by detroitm2 View Post
Not sure where you can up with 24 inches. Maybe I'm looking at the wrong formula, but I got the following:

((1125) / (RPM * 6 * (1 / 60))) / 4

At 3000 RPM, that works out to 0.9375 feet, or 11.25 inches.

1125 = speed of sound in feet per second.
6 = number of pulses per revolution in a 6 cylinder engine
1/60 = convert from minutes to seconds
4 = quarter the wavelength to cancel out the resonance.

This is actually an interesting idea, I'm just curious where in the exhaust you'd be able to put it. Perhaps right before the y pipe, and have it tuck back behind the exhaust can? Might be some room there.
Not 3 pulses as every cyl fires once every 2 revolutions of the crank? Like I said, don't trust my math.
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      08-24-2020, 08:45 AM   #29
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Originally Posted by cecaa850 View Post
Not 3 pulses as every cyl fires once every 2 revolutions of the crank? Like I said, don't trust my math.
Ah, that makes sense. I wasn't aware it took 2 full revolutions for all 6 cylinders.

So with that in mind, we're looking at a 22.5 inch pipe to cancel the resonance at 3000 RPM.
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      09-08-2020, 09:19 AM   #30
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For DCT owners with the Fabspeed sport cat and MPE, is the drone present even with the faps closed?
And how is it on the highway in sport +?
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Last edited by Nicname; 09-08-2020 at 11:49 AM..
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      09-08-2020, 09:54 AM   #31
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For DCT owners with a Fabspeed sport cat, is the drone present even with the faps closed?
And how is it on the highway in sport +?

I have a Fabspeed sport cat and an otherwise stock exhaust with no ASD. No drone at all.
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      09-08-2020, 11:48 AM   #32
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Quote:
Originally Posted by cecaa850 View Post
I have a Fabspeed sport cat and an otherwise stock exhaust with no ASD. No drone at all.
Sorry I meant for those with both of them installed. I'll update my post
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      11-17-2020, 05:47 AM   #33
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Quote:
Originally Posted by detroitm2 View Post
I have a 6MT with MPE. The drone exists cruising in 6th gear on the freeway at 80mph. Easy solution is to just run in 5th gear. Bit lower gas milage, but the drone goes away completely.
Does the drone only exists when cruising in the rpm range like for freeway driving? How about when accelerating through the gears around the 3k rpm mark - is the drone evident then?
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      11-17-2020, 08:54 AM   #34
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Quote:
Originally Posted by BMWF87Melb View Post
Quote:
Originally Posted by detroitm2 View Post
I have a 6MT with MPE. The drone exists cruising in 6th gear on the freeway at 80mph. Easy solution is to just run in 5th gear. Bit lower gas milage, but the drone goes away completely.
Does the drone only exists when cruising in the rpm range like for freeway driving? How about when accelerating through the gears around the 3k rpm mark - is the drone evident then?
I'm sure it's still there, but you're not sitting at 3000rpm for any period of time so it goes mostly unnoticed.
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      11-18-2020, 04:10 PM   #35
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Quote:
Originally Posted by BMWF87Melb View Post
Does the drone only exists when cruising in the rpm range like for freeway driving? How about when accelerating through the gears around the 3k rpm mark - is the drone evident then?
I have MPE and fabspeed. Drone is definitely there for both. As you cross through the 3000-3500 range during normal driving, you get that deep reverberation for a second or two. I drive mostly city and limited highway and it's never bothered me but I could see how those with long highway commutes would get tired of it.
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      11-18-2020, 04:17 PM   #36
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Quote:
Originally Posted by Mosely View Post
Quote:
Originally Posted by BMWF87Melb View Post
Does the drone only exists when cruising in the rpm range like for freeway driving? How about when accelerating through the gears around the 3k rpm mark - is the drone evident then?
I have MPE and fabspeed. Drone is definitely there for both. As you cross through the 3000-3500 range during normal driving, you get that deep reverberation for a second or two. I drive mostly city and limited highway and it's never bothered me but I could see how those with long highway commutes would get tired of it.
Thanks for that. The drone would definitely be accentuated by the downpipe right?

Not sure if you had the MPE first, but curious to know how much as a percentage the dp would contribute to the drone.
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      11-18-2020, 09:14 PM   #37
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Quote:
Originally Posted by BMWF87Melb View Post
Thanks for that. The drone would definitely be accentuated by the downpipe right?

Not sure if you had the MPE first, but curious to know how much as a percentage the dp would contribute to the drone.
I think it's mostly the MPE that drones but I'd imagine downpipe accentuates it. I did DP first with stock exhaust and there was pretty much zero drone with that combo.
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      11-18-2020, 09:20 PM   #38
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Quote:
Originally Posted by Mosely View Post
Quote:
Originally Posted by BMWF87Melb View Post
Thanks for that. The drone would definitely be accentuated by the downpipe right?

Not sure if you had the MPE first, but curious to know how much as a percentage the dp would contribute to the drone.
I think it's mostly the MPE that drones but I'd imagine downpipe accentuates it. I did DP first with stock exhaust and there was pretty much zero drone with that combo.
I'll be getting an MPE installed soon. No other mods done to the car. Have the ASD harness install, so just bracing myself on what to expect with the drone!
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      03-14-2024, 11:35 AM   #39
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I have F87 M2 MT and was thinking of getting MPE .. do you enjoy the MPE / is it worth it? How bad is the drone at 60-80mph!?? How loud is it on cold start up? Worried about neighbours getting upset …
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      03-14-2024, 04:21 PM   #40
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I would also NOT recommend the MPE due to drone.

I believe a dual exit exhaust from the downpipe back would be better with drone, as well as having an exhaust that completely channels through the muffler instead of the T like design on the MPE’s muffler.

If you have a DCT you should avoid the drone on the highway with the lower rpms of the 7th gear but I would still recommend another exhaust personally.
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      03-14-2024, 10:49 PM   #41
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Believe it or not.
Sportcat + MPE = 100% drone, wider range
Catless + MPE = 30% drone, narrower range
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      03-21-2024, 03:31 PM   #42
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So has anyone successfully dialed out the 3KRPM drone from the MPE with a resonator? I love the sound and appearance of the exhaust, but do wonder if that aspect could be fixed.
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      03-21-2024, 04:01 PM   #43
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I have an M235i with a full exhaust and MPE, plus a ***less downpipe. I don’t recall the drone being that terrible before, but it does sound a little annoying now.

You could do a vibrant resonator or a hemholtz one.
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      03-21-2024, 06:24 PM   #44
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I’ve gone through many different set ups between catless/HJS 300, m2 resonator + MPE, MPE w/o the res and nothing really worked. The res did not affect the highway drone but it did a little to help on the street.

The worst setup I had drone wise was the stock DP and MPE. The best I would say is the HJS+res+MPE, although I’m sure a stock exhaust would help even more.

Catless and HJS didnt change the drone for me to any noticeable levels but it did get a little quieter. Nothing really helped. I think the issue is in the single pipe exhaust and the design of the MPE only makes it worse than the stock muffler with the drone.
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