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2016 Dodge Challenger 392 Shaker
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Discussion Starter #1
Hey everyone,

I've had my '16 392 Shaker for a little under a year now; one of the first mods I did the day after purchasing was the mid-muffler delete (sounded beautiful, knew I had to do it instantly as my previous R/T was louder than a stock Scat Pack). Never had drone/resonance issues until about 2 months ago. Car began vibrating slightly in MDS to be noticeable, between 66-74 MPH, enough to vibrate the rearview mirror to where everything becomes blurry, other car headlights and shapes go flat, and standing street lights start moving in circles - essentially the mirror becomes useless.

I had taken it to my dealer that I used to work at twice - after keeping the car for several days, the techs said they found nothing wrong with the MDS system itself, no bad engine mounts either, no misfire. One said it may have been due to my mid-muffler delete causing resonance. I wasn't sure of this because the car had been fine for months before, but figured I'd give a try at changing out. So I just got Dynomax 24250 mini-bullets today, a common favorite I see for many 6.4L owners as better than the mid-muffler anyways. After driving with them, the vibration is still there and mirror is still useless. (to their credit, the sound of the vibration is a tiny bit quieter). Any clues as to other causes? Anyone else ever have this issue?

I'm not sure what else the cause could be. The unfortunate thing is I LOVE the MDS for trips because I drive on the highway a lot between states, and 70 MPH is perfect cruising speed for me - literally in the middle of the issue speed range.

Ultimately if I never find a fix, may just take the mufflers back off as looking at my in car dyno it seems I lost some peak power with the dynomax's (went from consistent 502 to 493 on some fun test runs), and then get a pcm, tune & throw on headers to perm disable MDS. I have a Tazer and run in Custom mode, but again my issue is I like to use ECO/Default mode for the highway as I take a lot of trips for family & friends. And for the cruising fun of a Challenger. 27-28 MPG in a 500 HP car is pretty wonderful.

990190
 

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2018 Scat Pack SHAKER in Plum Crazy
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My 2 thoughts are
1 - I never get MDS at 70MPH, but no long flat roads here. I typically only see it under 65.
2 - is the mirror loose?
 

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2016 Dodge Challenger 392 Shaker
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Discussion Starter #3
My 2 thoughts are
1 - I never get MDS at 70MPH, but no long flat roads here. I typically only see it under 65.
2 - is the mirror loose?
My MDS even comes on at 80 MPH; I'd always thought 70 would be pretty typical, I've seen RAMs engage as well at 70. But for youe 2nd question, I've once even popped off the entire mirror assembly and put it back on. That did not solve it.
 

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2018 Scat Pack SHAKER in Plum Crazy
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And while it is happening, if you tap sport mode, or the shifter paddle to lock it in 8 without MDS it goes away?

Any rattling from the rear? I read about the exhaust valves fluttering causing noise, and maybe pulsating.
 

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My MDS even comes on at 80 MPH; I'd always thought 70 would be pretty typical, I've seen RAMs engage as well at 70. But for youe 2nd question, I've once even popped off the entire mirror assembly and put it back on. That did not solve it.
Neither my previous 5.7 or my present 392 will go into, or stay in MDS at 80 mph, even when the road is flat as a pancake.

Might want to have another dealer check this out. Most folks over the years have said that their 392's don't engage at over 70 mph.
 

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Those of us with manual trans need not worry about the dreaded MDS drone. It will vibrate and rattle things in the car if using an exhaust that is not the stock factory issue for that car. It almost feels like driving across a washboard dirt road.
My '14 300C Chrysler w/hemi 5.7 had that issue until I used my Diablo i3 tuner to shut it off. It runs so much smoother and sounds great with the stock R/T exhaust off my '12 Challenger. Fuel mileage hasn't gotten any worse either, even with the 91 octane canned tune I installed in the car.
 

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2016 Dodge Challenger 392 Shaker
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Discussion Starter #7
I ended up getting the diablo tuner & just knocked the MDS off; but thank you guys for input!
 

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2015 RT 5.7 M6
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Might not be your problem but on my 2013 JGC I had noticeable vibes whenever MDS kicked in. Turns out my driver side motor mount was shot. Swapped the mounts out and the ride now is super smooth.
 
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