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Down pipe

Discussion in 'Turbo Tech Questions' started by vht, Sep 16, 2021.

  1. vht

    Joined:
    Feb 23, 2014
    Would there be much HP loss going from a 5 in down to a 4in? It seems you can find 4 in bends and flanges a lot easier.
     
    vht, Sep 16, 2021
    #1

  2. B E N

    Joined:
    Nov 22, 2016
    Not unless you are making some absurd power. Spool might be better with a 5. I went from a 3 to a 5 and that was the big difference I noticed. An 88mm exducer (the common s475/s480) wants 4.33" pipe, according to the 1.25x exducer size rule of thumb. Unless you are max effort I wouldn't worry about it. 5" is a fitment nightmare too!

    Try semi shops for anything 4"+. My local wrecking yard has a couple complete semi's I could pull the exhaust off of if I do another big single build.
     
    B E N, Sep 17, 2021
    #2
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