Question 97 silverado - installing dual inlet dual outlet flowmaster muffler issue

Discussion in 'Engine & Performance' started by polarisn1, Jan 4, 2017.

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  1. polarisn1

    polarisn1 GMFS Member

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    I have been researching this for a couple weeks now, and I can't seem to find any DETAILS on how to install this muffler:

    I want the Flowmaster Super 44 muffler with dual inlet and dual outlets. Part number 8425454 for the stainless steel one that I have selected.

    This muffler has 2.5 inch inlets/outlets which is fine. I can adapt them to the 1 7/8" OD pipes coming off the cats.

    My issue is this: the Flowmaster muffler states that it has a 5" center to center measurement of the inlet pipes. My truck appears to have a 6" center to center measurement right before the stock muffler- I crawled under it and measured.

    This ends up being a half inch difference for each pipe/muffler inlet to overcome. But, if the exhaust adapters are to slip-fit over the stock pipes and slip-fit into the mufflers, then it wont go in and play nicely. I plan on clamping the exhaust together with band clamps, as I currently don't have access to a welder.

    All of the research I have uncovered states that people have apparently put a single Flowmster dual inlet/outlet muffler on these 96-99 trucks with dual exhaust into the stock muffler, but they don't explain how they overcame this apparent issue.

    I prefer to put only one muffler on the truck, as this will also act as an H or X pipe as well. Plus, it's less expensive.

    I have my built parts list to do the dual exhaust myself, but am reluctant to order all of the parts if I am going to have a big issue with the muffler attaching to the stock dual pipes of the truck.

    Does anyone have first hand experience with this, or know where to find the threads about this?

    What I am looking to do:
    Flowmaster super 44 stainless muffler p/n 8425454
    Flowmaster dual exhaust pipes 2.5" p/n 15811
    assorted band clamps from summit of the appropriate size
    assorted exhaust hangers from summit as well

    I just replaced my plugged cats with Flowmaster y pipe p/n 2010023 (truck had an efficiency code for bank 2, plus I used a handheld thermometer to verify that the inlet of the cat was 100 degrees hotter than the exit (which is the opposite of what it should be)). Now that I have that corrected, the stock muffler is next to go. The truck has 208xxx miles on it.

    I did look at a complete cat-back system, but I am not interested in dropping that much coin.

    Any advice is appreciated - as I want to get parts ordered fairly quickly.

    Thanks so much!
     
  2. polarisn1

    polarisn1 GMFS Member

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    Anyone?
     
  3. Phildirt

    Phildirt n. fil-dert.

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    Can you summarize what you need in 1-2 sentences? That might help.
     
  4. Graystone

    Graystone Mmm Sandwich

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    Dnw to read that to help with hillbilly muffler
     
  5. polarisn1

    polarisn1 GMFS Member

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    I thought that fully explaining where I am at would help not waste other people's time when they ask questions. This way all of the information is present.

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  6. polarisn1

    polarisn1 GMFS Member

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    I don't understand what you wrote. A flowmaster muffler is a hillbilly muffler?

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  7. Graystone

    Graystone Mmm Sandwich

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    Yes. Garbage at best. But if you don't want performance and are looking for mouth breathing exhaust note than go for it
     
  8. polarisn1

    polarisn1 GMFS Member

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    Thank you for taking the time to read my post.
    I didn't ask for personal opinions on the muffler or brand. What I am asking for is ideas on how to mount the muffler to the truck given the dimensions I am facing.
    Are you able to assist in this fashion?

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  9. Machingeaneer

    Machingeaneer GMFS Member

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    If you can't figure it out, bring it to an exhaust shop.
     
  10. Graystone

    Graystone Mmm Sandwich

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    I didn't read it. You did not read my first post
     
  11. polarisn1

    polarisn1 GMFS Member

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    Of course I read your post. It offered little assistance to my original question


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  12. Hogg

    Hogg GMFS Member

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    To be truly effective at what an H-pipe or X pipe is supposed to do, you need an equal amount of piping before each inlet of the muffler. Because your GMT-400 truck moves all the exhaust over to the passenger side, there will always be more pipe in front of the drivers side exhaust.
    If I were you, I'd just run 2 smaller mufflers staggered to tune the exhaust properly.

    peace
    Hog
     
  13. polarisn1

    polarisn1 GMFS Member

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    Thanks for the response. So if I understand you correctly, the muffler should be the same distance to the manifold on each side, resulting in the mufflers being staggered.
    What I'm now curious about is the length of the pipe after the muffler. The drivers side will be significantly longer because it's traveling back to the drivers side. Dies this not affect the tuning of the exhaust? Or, is the only important part the distance between manifold and muffler?
    this is a good discussion, thanks you.

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  14. Phildirt

    Phildirt n. fil-dert.

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    Thanks you
     
  15. polarisn1

    polarisn1 GMFS Member

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    For What?

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  16. Hogg

    Hogg GMFS Member

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    The more tuning takes place pre muffler than post muffler.

    peace
    Hog
     

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