Sound Deadening and Interior Resonance

[WildJones]

Howdy folks,

I have been listening to sound clips on Youtube for the past week as I try and make up my mind on which mufflers I want to run on my Cuda with its new 440 stroker. When I had the 383 in it, it had some variation of Flowmaster 40 series. The car sounded decent when driving, but idle really lacked any muscle car feel (proof - https://www.youtube.com/watch?v=yjpZySdotmA) - due to the motor configuration. Sometimes at idle or when in gear and going slow, like when backing up, the exhaust would emit this horrible noise that felt like pressure in your ears. This is what I am guessing is considered interior resonance? Everyone familiar with the Flowmaster product line knows that their aggressive sounding mufflers suffer from lots of drone and interior noise. I like hearing the car from the inside, but I do not like the uncomfortable, intermittent noise that feels like pressure on my ear drums.

This time around, I would like for the car to have a nice sounding idle (subjective) and as little drone and interior resonance as possible. I was planning on installing some sound deadening before putting the interior back in, but here is my main question:
Those of you who have installed sound deadening and have a loud exhaust, how much interior resonance does the sound deadening actually take out?

Dynomax Super Turbos and Ultra Flows seem to be pretty popular options. Flowmasters seem to have extremes on both ends of the spectrum; some love them, while others hate the tinny sound - I agree. However, I came across a video of the Flowmaster Pro Series which sounds like a crossover between Flowmaster and Dynomax ultra Flow/Super Turbo sounds. I really like it, but I am nervous that I will get the terrible interior resonance issue again. 

[djw383]

Fat Mat Mega mat off eBay everywhere inside the car with headers and flow master 40's and I have no drone at all....

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[WildJones]

Has anyone else had similar or different experiences?

[moparman82]

I had fat mat too, took all the drone out of my built 340 with dual 3" flow masters that were dumped behind the axle

[soundcontrol]

I had terrible resonance in my car (convertible), I had Magnaflow, very loud ones, changed to Flowmaster 50 series, a bit softer, but still a lot of resonance, they sounded great exterior, nice rumble, and I think the resonance was due to bad headers, and a stainlesss steel exhaust system.


I had no damping inside the car at all. Now the car is in pieces, I have a new TTI system (not stainless), and new TTI headers and Dynomax mufflers waiting. I'm also changing the engine to a 6.1 Hemi so it will be a completely new setup, I will use Dynamat or similar when I put it together again. Resonance is hard to get rid of, most of the time it comes from the mufflers (acoustic), but it can also be mechanic, check so the exhaust system is haning free and not touching the body at any point, and the hangers have good rubber. Can be as little as the exhaust tips touches the rear valance, that can make the whole car resonate.

[Rdchallenger12]

Does stainless make a difference?

[soundcontrol]

Does stainless make a difference?

Yes, stainless steel has a little bit different sound then reglar steel. Some say they are louder, but I don't know, maybe "harder", but its not a huge difference, mufflertype has way more affect on the sound.

[HP_Cuda]

Fat mat with Dynomax VT mufflers and heck yes it made a difference!!!

 

[72bluNblu]

Probably late to the game here, but I'll chime in. I used FatMat "rattletrap" in my Duster, covered the entire floor and roof with it. It makes a huge difference in cabin noise. Not just the exhaust either, it does a great job with minimizing road noise and all of the body creaks and rattles these cars tend to have. I bought more to do my Challenger next.

I also run the DynoMax ultra-flo's on my car. Great muffler. Loud without being completely obnoxious, still manageable for long drives etc. I've never noticed a resonance problem with them either, at least on my Duster. It's a 2.5" dual system behind a set of Doug's headers.

This is just a clip at idle, it really comes alive when you get into the throttle.

https://youtu.be/62bjHlxzsoA

[EbodyPro572]

I'm using 'Second Skin' sound deadener & heat reflector.  Very high quality but kinda on the expensive side.  Great stuff!

[Racer57]

I have the Dynamat plus Reflectix and use Ultraflow mufflers. They were the perfect volume until the fiberglass packing burned out.

[WildJones]

I have the Dynamat plus Reflectix and use Ultraflow mufflers. They were the perfect volume until the fiberglass packing burned out.

Racer57 and 72bluNblu,
I appreciate the feedback and video clip of the Ultraflo muffler. It sounds great, but I have read a lot of folks mentioning that the welds bust or the fiberglass burns out - bummer!

I think I am going to try out Borla this time around with some XR-1 Sportsman mufflers (part no 40943) https://youtu.be/g2eIyHhUcak

Based on feedback from everyone here, I will be doing sound deadening for sure, though I think once I get the motor in the car and the electrical figured out that I'm just going to bolt the driver seat in and go for a ride  . Five years is too long to not have driven my car, I don't know how some of you guys with longer projects do it!

[72bluNblu]

I appreciate the feedback and video clip of the Ultraflo muffler. It sounds great, but I have read a lot of folks mentioning that the welds bust or the fiberglass burns out - bummer!

Welds bust?! I don't even see how that's possible unless you're dragging them about on the ground, and I certainly haven't heard of it. The welds on the set that I have are beautiful. Haven't heard anything about the packing being a problem either, and I have seen a TON of people that run and recommend the Dynomax welded ultra-flo's. I have almost 10k miles on mine now, no issues at all. And my 9.8:1 340 with ported heads blew the crimps out on the 2.5" Summit super turbo's that came with my 2.5" exhaust in a couple weeks.