Tune required with pre cat back exhaust?
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This is a discussion on Tune required with pre cat back exhaust? within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; Want to know if I need a tune if I go from the 2 bolt flange after the pre cat(thereby ...

  1. #1
    Registered User 100plus2Vegas's Avatar
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    Tune required with pre cat back exhaust?

    Want to know if I need a tune if I go from the 2 bolt flange after the pre cat(thereby eliminating the 2nd cat).
    14 sedan Limited: AEM intake, Tomioka IC hose, Cobb AP V3, Invidia down pipe with 3" cat, custom 3" mandrel bent single exhaust, Aem air fuel gauge,Cobb knob,Perrin Pitch Stop mount, SPT front strut tower brace, K-Sport coilovers@1.5" drop.

    07 Duramax LBZ- 26psi,intake, TBE, Diablosport programmer, Edge Insight with EGT, EGR block off, BD exhaust manifold, PPE fuel valve.

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  3. #2
    Registered User WRX-maniac's Avatar
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    Not sure exactly what part of the exhaust you talking about here. You can run a full cat-back, from the stock downpipe back without a tune. If you replace your stock downpipe with an aftermarket one, you WILL need a tune.
    2011 WRB WRX hatchback---Stage 2
    Stink-Eye Mob #301
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  4. #3
    Luke Skywalker Mikie13's Avatar
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    I see what you're saying...the stock downpipe is technically a 2 piece downpipe, with two cats in it.

    OP: what you'd need in order to do that (which I don't know why you'd do that anyway...) is a fully custom exhaust built by a custom shop. But considering you aren't eliminating the restrictive first cat, you'll still have a hindrance in performance.

    There's a reason why zero aftermarket companies manufacture just the second half of the downpipe...because it's pointless. To see gains, you need to replace the whole downpipe. And to do that safely and correctly, you DO need a tune for the aftermarket downpipe.

    Just get a downpipe and figure out a tune and go from there.
    The Hawk-Eye Alliance #90|The Blobeye Syndicate #0|The Stink-Eye Mob #0|N.E.R.D. Founding Member & #3
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  5. #4
    Registered User xFalleNx's Avatar
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    +1 to what Mikie said ^
    --Anthony 2011 DGM WRX stg2+sf intake WTFtuned ¯\_(ツ)_/¯

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  6. #5
    Registered User 100plus2Vegas's Avatar
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    Reason I ask is I'm not ready to buy an access port to tune for an aftermarket down pipe and intake.

    I work at a muffler shop and can make my own exhaust all day. I am merely asking if I can go from the 2 bolt flange after the pre cat(eliminating the 2nd cat) without a tune. Thanks for the help.
    14 sedan Limited: AEM intake, Tomioka IC hose, Cobb AP V3, Invidia down pipe with 3" cat, custom 3" mandrel bent single exhaust, Aem air fuel gauge,Cobb knob,Perrin Pitch Stop mount, SPT front strut tower brace, K-Sport coilovers@1.5" drop.

    07 Duramax LBZ- 26psi,intake, TBE, Diablosport programmer, Edge Insight with EGT, EGR block off, BD exhaust manifold, PPE fuel valve.

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