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  1. #1

    Default Aftermarket Catalytic Converter

    Has anyone ever used them? Since my last discussion about how to quiet down my exhaust, we came to the conclusion that high flow cats are nice, but don't really quiet down the exhaust. I'm looking for a midpipe solution and am willing to lose a bit of performance to retain the sound of my Flowmaster catbacks. I also like the idea of not having the gas smell in the garage from not having cats.

    I'm eyeing these Walker Exhaust ones on Summit. They are cheap and seem to be getting decent reviews as far as longevity. Any thoughts on them? What have you California guys done when you need new ones?
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  2. #2

    Default

    Not a fair comparison but for reference this is a Walker High-Flow on a 2.3 Turbo. I liked it.






  3. #3

    Default

    Thanks! Looks nice!
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  4. #4
    FEP Power Member smitty54's Avatar
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    I don't have a catalytic convertor on my 84 GT so to quiet down my exhaust I installed one of these Dynomax resonators along with my Dynomax super turbo muffler. It has a nice sound to it, but no way is it loud.

    "Have you ever noticed that anybody driving slower than you is an idiot, and anyone driving faster than you is a maniac."
    George Carlin, Rest in peace

    Rick
    84 GT Convertible
    68 Cougar XR7
    14 Ford Explorer Limited

  5. #5
    FEP Senior Member
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    Default

    I bought 2 of those convertors from summit. got my stang to pass emission test. but I do not remember it making the car any quieter.

  6. #6

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    Quote Originally Posted by smitty54 View Post
    I don't have a catalytic convertor on my 84 GT so to quiet down my exhaust I installed one of these Dynomax resonators along with my Dynomax super turbo muffler. It has a nice sound to it, but no way is it loud.

    Thanks for chiming in! I've been wondering about resonators! I know the OEMs usually use them to further quiet the exhaust on newer cars, but you don't hear much about guys adding them to older ones. Did you put them where the cats usually go? Since I had to extend my catbacks for the longer wheelbase, I might have room to do both high flow cats (for better performance) and resonators... hmmm...
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  7. #7

    Default

    Quote Originally Posted by bob85gt View Post
    I bought 2 of those convertors from summit. got my stang to pass emission test. but I do not remember it making the car any quieter.
    To be clear, I'm looking at more of a stock replacement type one (rather than high flow) like these:

    https://www.summitracing.com/parts/wlk-15038/overview/

    https://www.summitracing.com/parts/wlk-15146/overview/

    Are those the same ones? Were you coming from an off-road midpipe?
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  8. #8
    FEP Power Member smitty54's Avatar
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    Yes, it is in the place where the converter would be. It quieted the exhaust sound considerably.
    "Have you ever noticed that anybody driving slower than you is an idiot, and anyone driving faster than you is a maniac."
    George Carlin, Rest in peace

    Rick
    84 GT Convertible
    68 Cougar XR7
    14 Ford Explorer Limited

  9. #9

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    Quote Originally Posted by smitty54 View Post
    Yes, it is in the place where the converter would be. It quieted the exhaust sound considerably.
    Awesome, thanks!
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  10. #10
    FEP Senior Member BMW Rider's Avatar
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    Oct 2014
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    Calgary, Alberta, Canada
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    I was finding the sound levels too high with the Flowmaster super 40s I have. I measured the decibels and it was hitting over the limits for AutoX events locally at 104 Db. After much debate and research, I opted to try a set of Vibrant bottle style resonators to try and bring the sound down a bit without sacrificing the quality of the sound or adding too much weight. With them in place now, the sound is still much the same quality without the rasp at higher revs and the max Db is now at 96.

  11. #11

    Default

    Quote Originally Posted by BMW Rider View Post
    I was finding the sound levels too high with the Flowmaster super 40s I have. I measured the decibels and it was hitting over the limits for AutoX events locally at 104 Db. After much debate and research, I opted to try a set of Vibrant bottle style resonators to try and bring the sound down a bit without sacrificing the quality of the sound or adding too much weight. With them in place now, the sound is still much the same quality without the rasp at higher revs and the max Db is now at 96.
    Nice! Thanks!

    Looks like we have an answer!
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

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