08-19-2020, 09:01 AM | #24 |
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08-19-2020, 09:21 AM | #25 | |
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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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((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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08-24-2020, 08:45 AM | #29 | |
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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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09-08-2020, 09:54 AM | #31 |
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09-08-2020, 11:48 AM | #32 |
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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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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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11-18-2020, 04:10 PM | #35 |
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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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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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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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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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03-21-2024, 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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