Exhaust System Recommendation

Discussion in 'Engine Topic' started by Dan M, Nov 2, 2020.

  1. Dan M

    Dan M Member

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    I currently am running headers with 2 1/2" dual exhaust on my 81 with a 350. I am using Thrush turbo mufflers located under the rear seat area. The noise is kinda loud, so I was thinking of changing to a system like this

    https://www.jegs.com/i/Dynomax/289/89021/10002/-1

    Anybody have any experience with placing the muffler between the axle and gas tank? Did it help with noise reduction? Ease on installation? Thanks in advance.
     
  2. Dan M

    Dan M Member

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    Has ANYBODY located their muffler between the rear axle and gas tank???
     
  3. biker

    biker Veteran Member

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    Until someone has the time to weigh in, have a look at this thread: https://nastyz28.com/threads/dual-mufflers-or-transverse-pros-cons.332373/
    Personally, the right pair of mufflers under the floor wont be too noisy. I have Pypes 2.5 race pro, they are loud out the tailpipes, but I hear nothing from them through the floor.
    I like the idea of less weight with one muffler and hiding it in the factory spot, and if I knew for certain that it wasn't a restriction compared with 2 mufflers, I would probably do it. I will be upgrading to 3" soon, just because I can. :)
     
  4. Dan M

    Dan M Member

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    Thanks biker! I tried searching for this type of thread before I posted, but couldn't find it. I will go through it.
     
  5. biker

    biker Veteran Member

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    No problem! Search doesnt work so well, but that was a recent thread that I remembered. Pros and cons to both... I like not having that space occupied in front of the tank, but as tucked up as my mufflers are, my kid still managed to bash them somehow.
     
  6. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    I used Dynomax/Thrush system (89021) you referenced when I swapped engines over 12 years ago. (Basic GM crate 350)

    It works well, fit's good. Great sound at idle and not horribly loud when you get on it.
    The sound will vary quite a bit depending on your engine build and cam selection.

    (I had to make adapters to mid-length Hedman headers and could have done a better job of tucking the front pipes but that was on me.)
    If you use that system with full length headers... The fit is quite good.
    The pipes need to be trimmed to the proper length in the front and I had a local shop cut the tailpipe ends at a 45* angle to look more like factory tailpipes.

    I did not use the hangers they supplied with the kit and bought stainless steel band clamps to assemble the system.
    I had to use regular muffler U-clamps at the muffler connections due to the turns in the pipes there.

    My entire system is suspended by the factory transverse muffler mounting points and the headers. (No hangers in the middle or at the tail pipes.)
    This has caused no issues for over 50K miles and the aluminized pipes seem to hold up very well. No rust yet.

    The Pypes system is stainless steel and a very good system, but it's twice the price.
     
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  7. Zspoiler

    Zspoiler Veteran Member

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    Have you tried putting tailpipes and a crossover tube on your present system .It usually quiets things down
     
  8. Dan M

    Dan M Member

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    Haven't done much with the system yet, but had another thought. I am currently running full length headers. Would switching over to cast iron manifolds help to quiet things down? A nearby company, D&R Classic Automotive, sells a complete replicate system for a 74 Z28 with the transverse muffler from stock exhaust manifolds that looks promising. And will I loose a lot of power? I know it all depends on a lot of factors such as engine build, but ball park figures are fine. The car is more of a cruiser so I'm not looking for max hp. Thanks.
     
  9. Scott Sievers

    Scott Sievers Veteran Member

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    The original muffler goes between the axle and the gas tank, so yeah it works fine, and is actually pretty quiet if stock components are used. I just got the system I ordered from PYPES, its a 3" Stainless system, I got the street mufflers with it, hoping for quiet when idling and cruising and LOUD when you stomp the pedal, we will see how it sounds once installed.
     
  10. biker

    biker Veteran Member

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    Any mods that add power depend on moving more air in and out of the engine. Depending on what rpm your mods are designed to move more air at will determine how much your exhaust choice will impact the power increase. If your mods increase low end power and your cam is done by 5000rpm, I think you might be best off to go with the stock style system and manifolds.
    Since your goal is more towards quieting things, it might be the way to go.
    However, good long tube headers are universally agreed upon to be the easiest power increase for any engine. Good long tubes with good gaskets and a ball style header connector are not inherently louder than manifolds.
    Good long tubes and a quiet transverse muffler might give you the best of both quiet sound and power.
     

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