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Fitting secondary decat pipes

Arkious Nov 16, 2016

  1. Arkious

    Arkious Active Member Team Daytona Audi RS3

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    Hi guys,

    I bought a set of used secondary de-cat pipes, so doesn't come with any gasket or gasket material and bolts etc. I was just wondering what's best to use and where to get them from. Also what's the best way to go about fitting them? Is getting one side up on the axle stands good enough?

    Cheers
     
  2. 45bvtc

    45bvtc Well-Known Member Supporter Team Cornflower Blue Team Daytona Gold Supporter Team Sahara Silver Audi RS3 Audi TT Audi A1

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    Scorpion and Milltek are basically the same and I've fitted both on to owners RS3 cars; the only difference I am aware of is that the Scorpion pipes have stainless steel flanges and the Milltek mild steel; but the noise at the back is the same.

    IDENTIFICATION:
    1) The secondary-catalytic exhaust pipes are different; one straight and one bent: the straight pipe is fitted to the 'passenger' side of the car and the bent pipe to the 'driver' side

    2) Each of the secondary-catalytic converter/exhaust pipes are connected to the downpipes with three M8 nuts and to the rear exhaust silencer with sleeves that are fastened with two captive bolts and nuts

    Note: The secondary-catalytic converter/exhaust pipe(s) have three M8-studs fitted - and as Audi have been sufficiently thoughtful to use mild steel nuts to these mild steel studs then more than likely your nuts will have seized onto the studs; mine had at 3000 miles

    REMOVAL:
    3) Use an M13 ring spanner and release the nuts from the straight/nearside pipe; don't worry if the studs shear/break as you can drill the secondary-catalytic converter/exhaust pipe flange a 'clear' M9 diameter later

    4) Release the 2-bolts securing the rearmost exhaust pipe sleeve (no need to remove the nuts just release so as to release/rotate the sleeve) and pull the sleeve toward the front of the car - the secondary-catalytic converter/exhaust pipe is now free to remove

    5) Pull the secondary-catalytic exhaust pipe toward the back of the car and remove; store safely

    CAUTION: DO NOT contaminate, touch, whatever, the core of secondary-catalytic converter

    6) Remove the gasket and store safely

    7) Repeat exactly the same process on the bent/offside pipe

    8) Carefully clean both gaskets; if intact there's no reason why they can't be used again; alternatively, buy two new ones

    REFIT:
    9) Apply a thin smear of exhaust gasket sealant to one 3-pin gasket

    10) Fit three M8 x 30mm long setscrews (I always use stainless steel) to the 'offside' downpipe flange - apply as much Copperslip to the setscrew threads as you can - and fit the gasket

    11) Apply a thin smear of exhaust gasket sealant to both ends of one exhaust pipe sleeve and fit the sleeve to the by-pass pipe: DO NOT tighten at this stage

    12) Assemble the by-pass pipe to the M8 x 30mm long setscrews at the downpipe end and loosely fasten with M8 spring washers and M8 nuts. Slide the exhaust pipe sleeve over the exhaust silence pipe making sure the sleeve is central over the gap between the pipes: DO NOT tighten at this stage

    MAKE SURE to rotate the bend in the pipe to the in-side:

    Cats.JPG


    13) Nip the 3-setscrews/nuts at the front end

    14) Nip the 2-bolts/nuts at the rear end

    15) If all looks properly aligned tighten all 5-setscrews/bolts/nuts

    16) Repeat exactly the same process on the straight/nearside pipe

    17) Once done fire up and allow to warm through: check for exhaust leakage and allow the sealants to cure'
     
    RStu3 likes this.
  3. Arkious

    Arkious Active Member Team Daytona Audi RS3

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    perfect thanks very much :D I shall look for 6 M8 x 30 S/S nuts and bolts tomorrow at work tomorrow. Thanks very much for the very detailed installation :D
     
  4. St53daw

    St53daw Active Member

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    What does the secondary decats delete actually do ? Just that mine has already been done ? Just wondered if there was any benefits to them ?
     
  5. Arkious

    Arkious Active Member Team Daytona Audi RS3

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    from looking at videos on youtube, and having a read around it seems to be relating to the sound and a very minor (probably unnoticeable) power gain.

    I am (weather permitting) hoping to finally get round to putting mine on tomorrow so will report back :)
     
    St53daw likes this.
  6. 45bvtc

    45bvtc Well-Known Member Supporter Team Cornflower Blue Team Daytona Gold Supporter Team Sahara Silver Audi RS3 Audi TT Audi A1

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    The sound is richer - taste depending - and you're not driving around with very expensive secondary catalytic converters that don't do much anyway

    The motor does feel a tad sharper but you'll soon get used to any difference

    Downside: with or without secondary catalytic converter by-pass pipes the 8P RS3 will pass the emissions test but will not 'legally' pass an MOT as the 'tester' should 'count' the number of catalytic converters (as per the vehicles EC Approved) so best seek an MOT centre that employs a 'tester' that can't count.

    An Audi garage will fail an 8P RS3 with by-pass pipes...
     
    Last edited: Dec 9, 2016
    St53daw likes this.
  7. Arkious

    Arkious Active Member Team Daytona Audi RS3

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    goes to show how backward this country is... your emissions are fine but because it was there it has to be there... but your budget tyres that could risk you sliding out of control yeah they are fine :)
     
  8. 45bvtc

    45bvtc Well-Known Member Supporter Team Cornflower Blue Team Daytona Gold Supporter Team Sahara Silver Audi RS3 Audi TT Audi A1

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    Factual history: 30 July 2014 @ 8243 miles @ Stafford Audi. Pre-MOT check by non-authorised MOT tester with (secondary cat' by-pass pipes) and the CO was 0.02%. I'd questioned the issue but was told it'd be OK to test, hmmm.

    12 Sept 2014 @ 8243 miles @ Stafford Audi. Authorised MOT tester refuses to undertake MOT due to missing secondary catalytic converters (I did say...) but once secondary cats were collected and fitted (a bit embarrassing for them...) the CO was 0.01%

    Note the 0.01% CO difference. The pass limit is 0.20% CO.

    Emissions Directive EEC-91-441, a component of the whole Type Approval of Motor Vehicles, is mega important and an MOT tester is supposed to 'test' in accordance with the approved build i.e. if it has 10 x cats to meet EEC-91-441 emissions then it should have 10 x cats for the test irrespective of whether they work or not as that'll be down to measurement.

    I could argue that driving a motor vehicle with secondary cat' by-pass pipes on UK, or European, roads is illegal (Milltek ones have a label 'not for road use' on 'em - see photo) as the vehicle does not comply with Approved Details; but then again I do and don't take my car for MOT to an Audi dealership.

    Not for road use.jpg
     
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  9. Arkious

    Arkious Active Member Team Daytona Audi RS3

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    I promise I didn't remove the not for road use badges :busted cop:

    but on another note,l I failed to install it. Not as easy as I hoped it would be. the nuts are quite rusted and the 13mm spanner just doesn't fit at all, spinning over the nut without any bite. On top of that I just couldn't get the height I needed to get under the car. So think its a garage jobby :(
     
  10. 45bvtc

    45bvtc Well-Known Member Supporter Team Cornflower Blue Team Daytona Gold Supporter Team Sahara Silver Audi RS3 Audi TT Audi A1

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    You need the right tools, Jay, for certain. I've broken a few studs in the process but never yet failed but I do have a pit and therefore good access.

    You wanna drive down here to me? OK, it's a long way for a 1-hour job but the offer is there...

     
  11. Arkious

    Arkious Active Member Team Daytona Audi RS3

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    I am going to wait till I get the set of ramps off my mate, hopefully this gives me a bit more access. Now knowing how much of a pain it is to get to I'm tempted on gutting the cats instead so there's no need to keep getting them on and off.

    Cheers for the offer tho :)
     
    45bvtc likes this.
  12. 45bvtc

    45bvtc Well-Known Member Supporter Team Cornflower Blue Team Daytona Gold Supporter Team Sahara Silver Audi RS3 Audi TT Audi A1

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    Note: other's that have done this (gutting) usually fit a straight through pipe through the cat body; just sayin' :hi:
     
  13. Winternacht

    Winternacht New Member

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    Really curious what it does to the sound...

    Keep us updated ;)
     
  14. 45bvtc

    45bvtc Well-Known Member Supporter Team Cornflower Blue Team Daytona Gold Supporter Team Sahara Silver Audi RS3 Audi TT Audi A1

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    Provides a likeable (for me) richness to the rear end - secondary cats just dampen the noise; if you're local come and listen... :yum:
     
  15. Arkious

    Arkious Active Member Team Daytona Audi RS3

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    you wouldn't happen to know the internal diameter of the cat would you :D
     
  16. 45bvtc

    45bvtc Well-Known Member Supporter Team Cornflower Blue Team Daytona Gold Supporter Team Sahara Silver Audi RS3 Audi TT Audi A1

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    57.2mm pipe bore, Jay

    P1040176.JPG

    P1040177.JPG
     
    Arkious likes this.
  17. Winternacht

    Winternacht New Member

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    Living in Belgium...so a little bit to far..

    You still have the original primary cat?..maybe a little movie would be nice ;)
     
  18. 45bvtc

    45bvtc Well-Known Member Supporter Team Cornflower Blue Team Daytona Gold Supporter Team Sahara Silver Audi RS3 Audi TT Audi A1

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    Primary cat still fitted; and here's a start-up and drive off (to dry the brakes) with RS3copilot doing the honours:



    Hope this helps...

    PS: my Lotus Elan Sprint 5, owned and maintained for 37-years, is shown next...
     
    Last edited: Dec 15, 2016
    Vito, Arkious and Jake 61 like this.
  19. Arkious

    Arkious Active Member Team Daytona Audi RS3

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    Your a star, cheers :)

    It's booked in next week to get it fitted in my Revolution Motorsport next Friday. They have assured me that it will pass its MOT without the cats in place and started quoting Subaru having the option to come from factory with and without this secondary cat. My reply was yeah but if it didn't come from the factory with the secondary cats then it won't have to be there for the MOT, where as those that did have them from the factory and have since had them removed will fail. He said nope, secondary cats are not a legal requirement and are only in place for manufacturers to meet their own targets.

    So I'm going to buy the pipe if I can find it and then see if they will gut and fit the pipe instead for me.
     
  20. 45bvtc

    45bvtc Well-Known Member Supporter Team Cornflower Blue Team Daytona Gold Supporter Team Sahara Silver Audi RS3 Audi TT Audi A1

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    Hmmmm... [​IMG] Hope your man is correct Jay but an MOT failure/rejection can be where: "A CATALYTIC CONVERTER MISSING WHERE ONE WAS FITTED AS STANDARD is the reason for rejection." See item #3 in column #3:

    MOT Cat test failure.JPG

    Like I say, I don't have my RS3 MOT'd at an Audi dealership (see #8 above) as them guys can count.....
     
  21. bobby_s3

    bobby_s3 Active Member

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    Bringing up an old post, but with these fitted anyone have any issues with Audi warranty? Seen as though i have recently found out i have Audi warranty :frown:
     
  22. 45bvtc

    45bvtc Well-Known Member Supporter Team Cornflower Blue Team Daytona Gold Supporter Team Sahara Silver Audi RS3 Audi TT Audi A1

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    Stafford Audi were OK with mime bobby but I've never had an RS3 warranty issue so they weren't tested; for sure if you did have an 'engine' issue then Audi would prefer/want it back to STD before undertaking any checks and or work. My secondary cats are still in the loft and will be staying there for some time yet.
     
  23. bobby_s3

    bobby_s3 Active Member

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    Thanks for the quick reply! Think I'll be buying myself a set of Scorpion ones this week! Got a trip planned to VW days in France with 3 other cars. So want the tunnel run to sound best as I can! Haha

    Sent from my SM-G925F using Tapatalk
     
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  24. Arkious

    Arkious Active Member Team Daytona Audi RS3

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    I've had no bothers with Audi warranty since having them on, but not done an MOT yet. They really do make it sound better... wish I could go primary decat but that's just naughty
     
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  25. 45bvtc

    45bvtc Well-Known Member Supporter Team Cornflower Blue Team Daytona Gold Supporter Team Sahara Silver Audi RS3 Audi TT Audi A1

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    Oh to be young again...
     
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  26. RSTHRILLER

    RSTHRILLER LOVE 5 BANGERS

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    I have some 8v secondary decat pipes pm for 8p aswell
     

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