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3.73s to 3.31s

Discussion in '2015+ S550 Mustang Talk' started by Jrt, Sep 15, 2018.

  1. Jrt

    Jrt Member Established Member

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    Hey guys need some help,I have a 2015 gt performance pack with 3.73s it is a manual car that is boosted has around 700whp ..so 1st gear is useless my question is would 3.31s be my best bet and also di I need to have the car returned for the gears beings that it's a manual car?

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  2. kcobra

    kcobra MUSTANG MANIAC Established Member

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    I put some 3.31's in my BOSS with around the same power also. I love them. More usable gears. The only downside is you can actually bog in 6th when going up a small grade and not going fast enough. It takes a bit to get used to. But I would recommend it.
     
  3. Jrt

    Jrt Member Established Member

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  4. kcobra

    kcobra MUSTANG MANIAC Established Member

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    No. Just reprogrammed the differential calibration for the speedo correction.
     
  5. scotmach

    scotmach Active Member Established Member

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    There are no changes made in the PCM on 2015+ cars since the information is stored in the BCM. You will need to address that should you swap to 3.31's.
     
  6. Jrt

    Jrt Member Established Member

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    Address what?

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  7. Jrt

    Jrt Member Established Member

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    Does anyone know if the pumpkins all interchange from EcoBoost to gt? So I can just swap the whole thing

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  8. ashleyroachclip

    ashleyroachclip Well-Known Member Established Member

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    Making two threads on the same topic I see .
    Not getting enough attention ?
     
  9. Jrt

    Jrt Member Established Member

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    Lmao..not that I just really need to know if they interchange before I make a purchase tomorrow

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  10. Jrt

    Jrt Member Established Member

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    I'm about 100 percent positive that they will

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  11. ashleyroachclip

    ashleyroachclip Well-Known Member Established Member

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    Only because you had to quote me from them both .......
     
  12. pwt's17

    pwt's17 New Member

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    Seems I read that the 4 and 6 cylinder pumpkins are aluminum, while the GT pumpkin is iron or steel.
     
  13. Jrt

    Jrt Member Established Member

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    I believe I've found out through several calls that there is a Aluminium and steel version for sure, they are all the exact same except those features and gearing.

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  14. pwt's17

    pwt's17 New Member

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    My research suggests the change to steel on the GT was for strength. Apparently the aluminum version was thought to be too weak for 435 horsepower. I would think putting the aluminum pumpkin behind 700 horsepower would not end well.
     
  15. Jrt

    Jrt Member Established Member

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    I agree..I found a cast steel housing with 331s,thanks for the response

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  16. scotmach

    scotmach Active Member Established Member

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  17. Jrt

    Jrt Member Established Member

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    Oh..so after finally talking to with my tuner he made it clear there will be no need for a retune on my year with a manual..

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  18. CobraBob

    CobraBob Authorized Vendor Premium Member

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    You will need to correct the speedometer reading for the new ratio.
     
  19. Jrt

    Jrt Member Established Member

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    I thought the same but my tuner is telling me after a few drive cycles it will correct itself

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  20. scotmach

    scotmach Active Member Established Member

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    kcobra likes this.

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