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Pre-cat strip out mod (piggie)?

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by GeoffDunk, Sep 1, 2013.

  1. GeoffDunk
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    GeoffDunk Member

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    Has anyone done the the S4 pre-cat strip out mod, or as them Americans call it, "piggies"?

    I was just wondering what is needed and what the real benifits are?
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  2. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    Main one is it sounds great. It's doable diy justvwith a decent selection of tools inc extensions to facilitate access.
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  3. GeoffDunk
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    GeoffDunk Member

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    Cheers for the speedy reply, do you have any more details or do you know of a how to guide anywhere?

    If the motor is breathing better does it change the torque curve and if so, in which way?
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  4. GeoffDunk
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    GeoffDunk Member

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    #4
  5. ricostuart
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    ricostuart Active Member

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    Want to do mine as well, but I have a tiptronic, which doesnt seem to have any guides for.
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  6. dualmono21
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    dualmono21 Well-Known Member

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    Yes

    I did mine which is a tiptronic a while back
    Main benefits are increase in torque and increase in power
    Most noticeable differances are the responsiveness of the engine ie. How quickly it revs
    And the increase in noise ... Not everyone wants this as when combined with a non resonated exhaust
    The car drones badly

    You also have to be aware of the check engine light , which will come on after roughly 30-40 miles
    Both the methods described in the american threads didnt work
    And the only alternative was to program them out

    The job itself will take some time as accessing the manifolds is not a 2 minute job
    I did mine on my driveway but i wouldnt advise doing this on axle stands and you need clearance to get the cats out and away from the car
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  7. GeoffDunk
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    GeoffDunk Member

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    Could you explain a bit more please, can this be done with VCDS or is a 3rd party required?
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  8. dualmono21
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    dualmono21 Well-Known Member

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    No im afraid this cannot be programmed out with vcds
    Basically the car will throw a check engine light every 10 miles or so
    As the pre cats deal with the extra fuel thats put in at start up
    Once you remove the pre cats , the ecu realises that the fuel trim isnt working correctly
    And throws a code up
    The only way thats guarenteed to work is to remove the lines of code
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  9. Paul @ Unit
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    Paul @ Unit Active Member

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    need to do this too. already have my lambdas mapped out. just need to find the damn time
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  10. dualmono21
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    dualmono21 Well-Known Member

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    may well be a lot easier physically on a v6 than on the v8
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  11. Paul @ Unit
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    Paul @ Unit Active Member

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    trust me there inst much room either. not much difference at all. im a vehicle tech myself and it annoys me im doing everyone elses cars and not my own. finding time is so annoying
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