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New 3'' Manta exhaust,does it quieten down after carboning up

Discussion in 'VF Holden Commodore (2013 - 2017)' started by VFSSVfan, May 16, 2019.

  1. VFSSVfan

    VFSSVfan New Member

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    Hi,just fitted a new 3 inch system,hurricane header & complete manta 3'' stainless steel system including hiflo cats to my vf ss series2 LS3 manual that has lsa supercharger & mild cam..

    Like the deep note but it's a bit loud even though it's the quietest version available of the manta exhaust.
    Will it quieten down much as it carbons up or should I fit the standard bimodal flaps to the manta mufflers?
    Thanks in advance for your advice.
     
  2. lmoengnr

    lmoengnr Well-Known Member

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    Fit your bi-modal valves to the current mufflers.
     
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  3. stooge

    stooge Active Member

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    I doubt it will quieten down much over time.
    with the bimodal flaps you need to workout whether your mufflers are like this design
    [​IMG]

    you see the valve is on the "straight through" pipe so when it is open you are essentially deleting the muffler and when it is closed the muffler will run the gasses through the baffles and quieten it down.
    if your muffler is already running everything through the baffles then adding the bimodal valves wont change too much apart from turning the dual outlet into a single so it might drop the noise a bit but not as much as you need.

    if you have the muffler like the picture with a straight through type pipe then adding the bimodal valve to that outlet will quieten it down a fair bit.
     
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  4. Unicorn

    Unicorn Member

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    Its the cats helping make it louder.
    If they are 100 cell cats you may as well have no cats,they are there for looks mostly,maximum flow and noise to go with it.
    The noise difference between the same cat back system with stock cats and 100 cell cats is huge.

    Edited
     
    Last edited: May 16, 2019
  5. BlackVXGTS

    BlackVXGTS Well-Known Member

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    They won't get quieter, if anything they will get louder.
     
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  6. PeteSS

    PeteSS Active Member

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    Mines similar set up, LS3 with Magnuson supercharger and a cam.

    It had a full 3 inch Pacemaker system ( 1 7/8 inch headers, 100 cel cats). hideously loud.

    Put a 2.5 inch Hurricane cat back with quite restrictive mufflers. Noticeably quieter when driving, though still too loud at idle, which i'm guessing due to the cam.

    Like Stooge said you could be wasting your time putting the bimodal flaps on your mufflers. Try blocking off one of the outlets and see if it makes a difference
     
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  7. vr304

    vr304 Well-Known Member

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    Would expect it to get louder if anything once it carbons up mate
     
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  8. gtrboyy

    gtrboyy Well-Known Member

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    Yep will get louder after a few heat cycles.

    Bloke at work has whipple blown 7 litre vf clubbie...with bi-modals closed you'd never guess it had 700rwhp
     
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  9. Strattos

    Strattos Member

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    If it's any help, I've just had a new exhaust system installed and as others have said, will get louder if anything. Now have 1000ks on it.

    No blower or cam on mine, but with engine-back 3" with 1 7/8 headers (all DPE) bimodals made a decent enough difference.

    Not sure if its the same as the pictured muffler design above, but for me makes enough of a difference to not worry the neighbours, which is really the only reason I had them fitted - that and being able to relax at stop lights with a copper behind you.

    Big enough difference at idle with this setup to make it worthwhile.
     
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  10. abuch47

    abuch47 Active Member

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    Does anyone else notice any rattle from an open aftermarket system with bimodal closed?
     
  11. kleanphil

    kleanphil Active Member

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    Hi, like this ( X-Force)


    I managed to get both replaced after a year under warranty , the other butterfly got stuck
     
  12. abuch47

    abuch47 Active Member

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    Can't watch but more so just tinny rattle sound when bimodals are closed, probably just the gases vibrating the flap creating metal on metal sounds.
     
  13. dimetime

    dimetime Active Member

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    yer my dpe 3inch system rattles with the bimodels closed, ended up taking out the fuse so it's loud thought the whole rev range rather then 3k onwards
     
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  14. abuch47

    abuch47 Active Member

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    There is a $150 relay/fuse tap on ebay that allows fully on/off bimodal with remote. Really easy to turn off when you get home or driving past cops.
     
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