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Discussion Starter · #1 · (Edited)
Hello,

I have a 2018 EB AT premium convertible (no performance package). Recently I got the MBRP street series cat-back. I chose this b/c a lot of users said it had basically no drone. Now technically it's noted as being for the fastback, but with spacers, my mech was able to get it to fit. Sounds great. But drone was bad - as many of you know, need to keep the wife happy. So I tried a small resonator. Then I tried the Vibrant ultra-quiet resonator. Calmed the noise a little but, but the drone is still bad (especially with the top down of course). So far, I've sunk in $1,000 with parts and labor so now I'm wondering what to do. Some options I'm considering (but would love to not reduce volume too much if possible):

1) I just bought some garage ramps so I was going to try to tweak how far back the exhaust tips sit (I figure moving them a little further out MIGHT help since the resonance would happen a little less under the car). I believe I can do this with simply an allen wrench?

2) I could try the J pipe / Helmholtz resonator idea. Note the worst resonance is around 1,600 to 1,700... so what length should I use in average 70 degree weather? This sounds promising but I'm guessing will cost me another few hundred - since I don't know how to weld.

3) I could reinstall stock - but then I feel like I'm admitting defeat and I'm thinking "someone has got to have solved this"!

4) Can I use stainless steel wool somehow to help? I've read some guys do this

5) I could try these... maybe combined with adjusting the position of the exhaust tips Amazon.com: Car Chemistry 2DI03L CC Inserts-Insert 2 Disk Mufflers Fits 3 in. Dia. Pipe CC Inserts-Insert 2 Disk Mufflers: Automotive

6) I could reinstall stock resonator or keep the Vibrant one and go with low drone axle backs???

PS If I do the exhaust silencers (option 5), can I just insert them in the small length of pipe behind the mufflers and leading into exhaust tips?

Thanks for hearing me out. Hoping to tap into this group's wisdom. Thanks!!!
 

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My wife has a 2019 vert and I installed the 2018-2021 GT oem quad tip non active mufflers with a CVF resonator delete. Sounds great with zero drone. 10spd with 3.15 gears.
 

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I have a PP couple with active exhaust and no resonator. In track mode there is a drone at that rpm. It is there in quiet mode as well but you can't really here it. Just the nature of the beast at that rpm. The only way to quiet it would probably be either option 2 or 3. I don't see any other way around it. It's not as noticeable with a manual as you are hardly ever at that rpm range with driving. So unless you want to manually shift....
 

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I tried several configurations between my 17 and 17 Ecoboost Mustangs. None of the made any noticeable difference in power.

1. On the 15 I replaced the stock mufflers with Magnaflo 14" long oval mufflers with the stock resonator. This was no louder or different sounding than stock.

2. Still with the Magnaflos I replaced the stock resonator with a Y pipe. This gave me a deeper and ever so slightly louder idle. At WOT it had a smooth and louder but not so much that it drew any attention. At cruise it was just as quiet as stock and there is zero drone. This configuration stayed on the 15 until it was totaled.

3. First change on the 17 was to remove the stock resonator and replace with a Y pipe with the stock mufflers. Again this was really no different than stock.

4. Still with the Y pipe I replaced the stock mufflers with 6" diameter 10" long race mufflers. This gave me a very nice sounding idle and a glorious howl at WOT. Cruising it was louder but not objectionable but with even the slightest application of throttle the volume would almost go up to the same level as WOT. I could not live with that with a car intended for daily driver duty.

5. Still with the race mufflers I reinstalled the factory resonator. This turned out to be the perfect exhaust for me. It has a nice idle and the howl at WOT, not quite as loud and is as quiet as stock while cruising.

Just to reiterate, none of these configurations made enough difference in power to be noticeable. All of these configurations were with a car with a Stage 1 tune.

If you are running a catless down pipe you can expect anyone of my configurations to be louder.

Also, both my cars are manuals and most all of my cruising is in the 1500 to 2000 rpm range and I have never heard any of the classic drone that happens when you reach a certain rpm.

FWIW, a buddy of mine bought a MBRP street exhaust for his 15 GT from some one that took it off because it was to loud. He used it for a couple of weeks and could not stand it because it was to loud. He wound up with the stock mufflers and an x pipe.

Sent from my motorola one 5G using Tapatalk
 

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Discussion Starter · #6 · (Edited)
Thanks that's helpful. I did mess around today with how far the exhaust tips stick out - as suspected, not very helpful. I plan to try the Car Chemistry product, and just place them right in the tips to see if they kill the resonance, before I place them in front of the mufflers. Lesson learned I think is to do axle-back in the future and stick with stock resonator. And yeah, wasn't expecting power per se - just wanted some fun audio factor when WOT.
 

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Complicating your issue is the fact these cars employ active noise canceling. I would imagine that's why the drone is worse for you with the top down; because the speakers do not have the power to overcome ambient noise in the open air.
 
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