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Thread: High Flow / Ultra High Flow Metal Core Catalytic Converters

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    Jr Member G ~ MINI's Avatar
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    Default High Flow / Ultra High Flow Metal Core Catalytic Converters

    Hey Guys
    Happy year !!

    I wanted to get some feedback on High Flow / Ultra High Flow Metal Core Catalytic Converters.
    What are you using... Was there a HP increase... CEL issues... Did it change the exhaust note?

    Thanks
    Joe

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    Moderator S.F.W.'s Avatar
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    Default Re: High Flow / Ultra High Flow Metal Core Catalytic Converters

    I can't speak to the non turbo platform, but on the Speed3 moving from a dual cat solution to a single high flow does increase HP. Some change in the exhaust note, but not drastic unless a larger diameter exhaust pipe is added, or a straight pipe solution.
    2010 Black Mazdaspeed 3 - Lightly modded

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    Jr Member G ~ MINI's Avatar
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    Default Re: High Flow / Ultra High Flow Metal Core Catalytic Converters

    Quote Originally Posted by S.F.W. View Post
    I can't speak to the non turbo platform, but on the Speed3 moving from a dual cat solution to a single high flow does increase HP. Some change in the exhaust note, but not drastic unless a larger diameter exhaust pipe is added, or a straight pipe solution.
    Thanks !!
    I can only assume the same would apply to NA with less HP gains than on Speed3 but more importantly
    keeping the high exhaust flow so the turbo spools up faster ...
    I want to replace the OEM Cats because they are getting old (possible flow loss and HP loss)
    and cuz it maybe better for the environment (ok ..dont laugh too loud... p.s. im also a
    environmental science/ geography major)...

    Right now just looking at it from cost per direct HP gain to a overall performance gain
    plus how much / big a new high flow or Ultra high flow metal core cat
    ( https://www.yonaka.com/category_s/390.htm or
    https://vibrantperformance.com/catal...d2f4f5fc77cfe5
    is needed to resume being emission compliant when swapping our pre and aft OEM catalytic.
    Im looking into which is a better swap and how cells per inch is needed to replace OEM pre and aft and stay legal and CEL free.

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    Jr Member G ~ MINI's Avatar
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    Default Re: High Flow / Ultra High Flow Metal Core Catalytic Converters

    As you may know when i installed new headers last year the pre Cat was removed and OEM Mid Cat remained.
    Was told many times the mid cat is useless and should just be removed when doing just a cat back exhaust.
    I finally got around to removing the OEM mid cat and adding a Ultra High Flow Cat (metal core 200 Cell)
    at the Mid Cat Location. Exhaust sound has changed. It sounds more angry , raspy , a deep throaty sound.
    I think this aloso conservatively added 1-2 HP...but more importantly increased exhaust flow and responsiveness under 3K RPM
    which will certainly help when i swap out the OEM Cams for stage 1.5 cams (April) making engine breath easier
    and exhaust faster which results in increased scavenging.

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