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Thread: Muffler Help!

  1. #1
    Join Date
    May 2003
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    Colchester, CT, USA
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    I am signed up for two PDA events this spring. Unfortunately they are very restrictive on the sound limits. No problem I thought, I'll just go get a stock muffler and bolt it right in!! WRONG!! I can't find a non performance muffler that will fit!! 19" over all, 3" ID/OD.......... Anything with a 3" pipe (truck) is much longer.

    I'm only going to be using this set up twice and it's just to get used to the new car (so I don't care if I lose some power) so I don't want to build a whole new exhuast....

    Any ideas??
    Jeff L

    ITA Miata



    2010 NARRC Champion

    2007 NERRC Championship, 2nd place
    2008 NARRC Championship, 2nd place
    2009 NARRC Championship, 2nd place

  2. #2

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    Magnaflow has an 18" racing muffler with 3" inlet/outlet. Part number is 14249 (Summit Racing number is MPE-14249) These are 5" x 8" oval. Dynomax lists an oval 19" with an offset 3" inlet, center 3" outlet outlet. Summit part number WLK-17221. Borlas has one but it's a bit pricy ($240), part number 40670

    I use a 6" round Magnaflow and am very happy with the noise reduction and quality. According to the dyno, a straight pipe, a Dynomax, and the Magnaflow are all about equal, slight edge maybe to the Magnaflow (wasn't repeatable). The Magnaflow was noticably quieter than the Dynomax.

  3. #3
    Join Date
    Jan 2004
    Location
    Camas, WA
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    magna flow, plus a sound elbow works wonders.


    Marcus
    Marcus
    miller-motorsports.com - Its always an Adventure (and woefully outdated)
    1.6 ITE/SPU/ST2 Turbo Miata (in pieces... err progress)

  4. #4
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    Sep 2004
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    cromwell ct
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    Jeff,
    You heard my car last season (loud). That was a dynomax. Not quiet enough for LRP muffled days. Make sure you get the right dynamax. They're not all the same.

    R
    Rob Breault
    BMW 328is #36
    2008 Driving Impressions Pro-ITA Champion
    2008 NARRC DP Champion
    2009 NARRC ITR Champion
    2009 Team DI Pro-ITR Champion

  5. #5
    Join Date
    Aug 2005
    Location
    Austin, TX
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    150

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    If you can extend the pipe to clear all body work a Supertrapp diffuser setup works great to quiet down the car and should be easy to add and remove.

  6. #6
    Join Date
    May 2003
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    Colchester, CT, USA
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    Default

    Magnaflow has an 18" racing muffler with 3" inlet/outlet. Part number is 14249 (Summit Racing number is MPE-14249) These are 5" x 8" oval. Dynomax lists an oval 19" with an offset 3" inlet, center 3" outlet outlet. Summit part number WLK-17221. Borlas has one but it's a bit pricy ($240), part number 40670

    [/b]
    I don't think any performance type muffler is going to do the job unfortunately........
    Jeff L

    ITA Miata



    2010 NARRC Champion

    2007 NERRC Championship, 2nd place
    2008 NARRC Championship, 2nd place
    2009 NARRC Championship, 2nd place

  7. #7
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    Nov 2004
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    Ligonier, PA, USA
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    1,676

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    Any ideas??
    [/b]
    What about a resonator? No restriction but reduces sound before the muffler.

  8. #8
    Join Date
    Oct 2002
    Location
    Concord, NH 03301
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    700

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    Get a 3" Cherry Bomb, Thrush, Purple Hornies etc. straight through glass pack.

    Now you say its too long. Yes I would agree. However, since they are a simple tube w/ insulation, then another tube inside that, get out a saw, cut it in half, then cut again to remove the necessary length, weld the outer tube back together. Not sure what the dB difference you will get, but it is cheap. You can also weld a super trap baffle on it, then bolt additional baffles & a cap onto w/o having to buy a $$upertrap.

    Option two would be to build a muffler w/ a 3"x whatever adapter welded on the end, then just flange it onto what ever you've got to work w/ on the car. You did say this was a temporary item.


  9. #9
    Join Date
    Feb 2001
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    311

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    I don't think any performance type muffler is going to do the job unfortunately........
    [/b]
    Actually, if you have a large enough muffler(s) it will be quiet enough. In some instances (pipe sizes, rpm range), a performance muffler can be quieter than a "stock" muffler without costing HP. Try to package a muffler(s) that has about 5x the volume of your engine. Use a muffler with a packing material as opposed to something with just baffles. If you are only thinking of bullet-style performance mufflers, I can just about guarantee it won't be quiet enough. Some people find where the exhaust exits the vehicle to have a significant effect on sound level (under the vehicle, behind the vehicle). If you know where the sound station is, at a minimum, direct your exhaust away from it.

  10. #10
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    Sep 2001
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    hampden,ma.usa
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    given this is a temporary installation why no just put an elbow on the existing outlet and run an additional muffleracross the back of the car from a bracket under the rear bumper. could be handy in the future when you want to load the car late at night without upseting the neighbors.
    dick patullo
    ner scca IT7 Rx7

  11. #11
    Join Date
    Oct 2002
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    Concord, NH 03301
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    But late at night when it's really quiet is the best time to find out just how loud your car is.

  12. #12
    Join Date
    Mar 2003
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    Somewhere in NC
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    I don't think any performance type muffler is going to do the job unfortunately........
    [/b]
    What are the sound limitations? I had a Thermal Research can on my car with nothing else (header straight to it exit in stock location) and my DB was always under 90...my friends always said it was too quiet as they could not hear me on the track, but that may be because there were so many loud ones out there...
    Evan Darling
    ITR BMW 325is build started...
    SM (underfunded development program)
    SEDIV ITA Champion 2005
    sometimes racing or crewing Koni Sports Car Challenge

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