Jones Maxflow - Not great?

Mopar Exhaust Systems

  1. MRGTX

    MRGTX Well-Known Member

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    I just installed these last weekend and I have a few miles on them, enough to render a verdict, which won't be a surprise if you read the thread title. So I'm running these behind the Magnum 5.9 (stock cam), Doug's headers, 2.5" pipes, no crossover.

    These are 18" long, 9" wide, 4" thick, offset on both sides. They fit really well fore of the axle and have exactly the same dimensions as the "stock style" cheap sheet metal mufflers that they're replacing.

    The good stuff: pretty cheap. They can be had for $35-$45ish depending on the size, model. They're supposed to be comparable to Magnaflow (similar design) but I'm just taking the internet's word for this. The welds all look nice, etc.

    Not so good stuff: First, they're surprisingly quiet. No, I don't want a huge amount of noise but I'd prefer if they were a notch or two (or three) louder...my wife said that she could barely tell the difference when we were driving around! That doesn't seem right.

    The more concerning part is that they sound "off." There is a bit more noise (over stock) from outside of the car but also a slightly displeasing quality to the sound that I can't quite identify. Under full throttle, near the higher end of the rev range (this is a Magnum so read that accordingly) they develop a "thudding" quality that just doesn't seem right to me. It's enough of a resonance to make the rear view mirror vibrate.

    What are your thoughts?
    Other folks have been happy with them. I'm wondering if I could have gotten a bad one. It's such a simple design that I just can't imagine how they could screw that up.
     
  2. 1Fast340

    1Fast340 Well-Known Member

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    mufflers sounds different depending on the engine they are behind,the gearratio,converter and where in the exhaust system they are and so on. it is what it is.
     
  3. MRGTX

    MRGTX Well-Known Member

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    Oh yes. This is very true. My combination isn't anything exotic. 4.10 gears, 2600rpm stall, mufflers in stock location.
    The one thing that I did which may be relevant is that I just used turn-down pipes after the mufflers and got rid of the pipes that went up and over the axle. This shaved ~25bs off of the car...but could this be the difference between "good" sounding exhaust and the odd "thudding" resonance that I have found? I suppose it could be.

    Has anyone else run these mufflers? Were you happy with them? what was your setup?
     
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    • 1Fast340

      1Fast340 Well-Known Member

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      Not having tailpipes could absolutly be part of the problem,partialy due to the pulses in the actual tubing and mufflers but also from the soundwaves bouncing under the car,especialy considering how much volume the car body has behind the rearseat that can amplify a reasonance tone so to speak.
      Worked with exhaustsystems for over 10 years and its realy hard to predict what works and what doesnt especialy as you go for larger tubing and alitle louder mufflers.
       
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      • Phil21502

        Phil21502 Well-Known Member

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        I tried the same thing on my 318 dart. Wasn’t happy with the sound. Switched to thrush welded mufflers and Love them. I think older engines sound great with chambered mufflers and modern day engines sound good with straight through mufflers. Now granite this is just my opinion.
         
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        • MOPAROFFICIAL

          MOPAROFFICIAL FABO Gold Member FABO Gold Member

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          Dynomax ultraflo is the muffler I use and always get the same compliments...

          "It sounds bad ass"
          "I really like the way that thing sounds"
          "Wow those ultras really made a difference, and the volume and tone is more bearable than a chambered at idle and cruise"
          "Seriously I can feel the difference...this thing got faster"
          You know... all stuff people rattle at you.lol

          The thudding could be a shitty characteristic of the design. . Or the case could be a lil high and hitting the car under wot...
          I always recommend pipes all the way to the bumper with tips 3 inches out past the bottom of the bumper...to avoid the smell being vacuumed back into the car.. of course a bad trunk seal will foil that if bad enough.
           
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          • 69_340_GTS

            69_340_GTS Well-Known Member

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            I think you need the tailpipes.
             
          • AJ/FormS

            AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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            I'm no fan of turndowns under the car. Don't like the sound under other cars and hate it under mine. I'm liking the 3" full-length tailpipes under my 68 Barracuda with LA360. And the 3-chamber Dynomaxers that TTI supplied in 1999 are still sounding great.
            __________________________________
            But the best mufflers I ever heard were on a 71 Demon340..... back in 71. The owner, a fellow high-schooler had just cut out the factory mufflers and installed straight-thru glasspacks. They were Orange and short and loud and obnoxious, perfect for a rebel 17 yearold. I forget the name of those. There were so many of those back in the day; Purple-Hornies, Cherry-Bombs, something Gooses, and these Orange ones, to name a few. Course today, I wouldn't even use 'em for resonators.They are totally cop-magnets.
            The dynomax turbos are quiet when cruising, and inside the car are not particularly loud at WOT. But at 6000 to 7000rpm, at WOT, they scream like banshees on fire.
            People even say they can hear the screaming demon sound, coming from a couple of miles away. Coming, not going;lol.
            Mine were new in 99,and still not rusted out, so they've done well.
             
          • dano

            dano Evil Handy Man

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            My dad runs a set on 3" exhaust through a nicely built 440, headers to tips. But its in a 66 Coronet 500. They sound great to me, but sound is very subjective. Most of those open flow, fiberglass/steel wool packed mufflers will change sounds with use and age.
             
          • Lelo Dart

            Lelo Dart * FABO Gold Member

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            Like mine but have tail pipes. To each their own.
             
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