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Any k03/s owners have negative comments about 3" downpip/decat?

Discussion in 'A3/S3 Forum (8L Chassis)' started by paultownsend, Dec 18, 2013.

  1. paultownsend
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    paultownsend Member

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    As above really, any negatives or downsides? Im going to fit one of the generic ebay 3" downpipes, then at a later date fit a Magnaflow 3" 200cel sport cat welded in. I have heard internet stories of old turbo's not liking the change in pressure and spitting their seals though the back box. It will be mated to a diesel straight through mid pipe ad OE rear box. RegardsPaul
    Last edited: Dec 18, 2013
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  2. 16Klappe
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    16Klappe Princess Slayer

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    What?

    Just get it fitted, they are great.

    I ran one for two years on a standard back box, as do 1000's of people.

    **** the internet, if it's not ASN endorsed its probably bull****.
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  3. kwistof
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    kwistof South East Events Moderator Regional Rep

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    I like this, but I cannot 'like' it as the website is not playing ball :(
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  4. paultownsend
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    paultownsend Member

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    Top chaps! My current flexi is leaking hence the need for a replacement. I'm hoping it will make the thing sound a little better too. Currently sounds like a wet fart
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  5. A3-Lee
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    A3-Lee Active Member

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    I wouldn't even bother with the sports cat bud 3 inch downpipe and decat is a win
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  6. paultownsend
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    paultownsend Member

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    There has been a few Vosa vans in the area recently. I wouldn't want to risk it.
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  7. kimhemm
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    kimhemm Member

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    If you get a good cat in there, the difference is really very small in power

    It's only if you want to use launch control it will make a big difference
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  8. 16Klappe
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    16Klappe Princess Slayer

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    I don't know who you are, but I don't like your attitude.
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  9. kimhemm
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    kimhemm Member

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    :unsure:
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  10. 16Klappe
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    16Klappe Princess Slayer

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    Sorry, I wasn't very clear there. I meant to say; you're wrong.

    Flow is flow, and a restriction in flow reduces power.

    Filling up your exhausts path with a catalytic converter is a great way of reducing flow. By all means bring up the legality of removing your cat, but why you would ever remove your cat, have it mapped out and then replace with a sport car I will never know.
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  11. Prawn
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    Prawn My other car is a MINI!!!!

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    he's right though jardo, the power difference between a high quality free flowing sports cat and a decat is very small.

    Don't be so obnoxious all the time!
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  12. kimhemm
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    kimhemm Member

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    I have done the test on a remapped 1.8T and the difference was 2 HP without a cat compared to a good free flowing sports cat

    So no, I don't really think I'm wrong and have a bad attitude
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  13. kimhemm
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    kimhemm Member

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    Exactly. Unless you are talking 4-500 HP and launch control a free flow 100/200 cell sports cat will be just about as good as no cat
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  14. 16Klappe
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    16Klappe Princess Slayer

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    I don't care.

    Why would you run a CAT, regardless of how slight the restriction is if you didn't have to.

    If sports cats are so great why don't you fit one Prawn...
    #14
  15. kwistof
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    kwistof South East Events Moderator Regional Rep

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    What make was the 'good free flowing sports cat' out of interest?
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  16. Prawn
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    Prawn My other car is a MINI!!!!

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    Because I'm cheap and won't pay for one.

    You're right in that ultimate power will indeed come from a decat over a sports cat, but for those not able / willing to swap it out every year, or find a friendly MOT place, if they can afford it without issue, a sports cat is only going to cost them a few bhp and save them a load of hassle.
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  17. paultownsend
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    paultownsend Member

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    I'm looking at the magnaflow cats. Circa £90.
    There used in the 42 draft exhausts and also in magnaflow's own systems. 100 or 200 cel.
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  18. ShoozY
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    ShoozY New Member

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    I ran one of the eBay downpipe and decat for a couple of years on a mk4 golf I used to have, the car was remapped before I fitted the downpipe, already had a non res cat back, the car was nippy and sounded goof, however when the downpipe was fitted it sounded evil on boost 😊, I was hitting boost hard and really early in the rev range, go for it mate you will love it!
    #18
  19. paultownsend
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    paultownsend Member

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    well offered £70 for the decat and its been delivered! just need to order gaskets and bolts from TPS and its a cold day in the garage!
    Does anyone have any tips or hints for changing the DP?
    #19
  20. jamiebennett81
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    jamiebennett81 Active Member

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    it doesn't work either way really

    running decat is illegal but the best for "flow" option, you just need a friendly MOT station

    running a 100cell or even 200 cell cat is almost pointless as again it won't pass emissions (certainly an old one won't) and so you are then stuck with a cat, which is restricting flow, and still won't pass an MOT....you might as well run with no cat (the only advantage being it looking semi legal should you get stopped by a clued up copper)

    or if you are that scared of getting done, then run a cat, but then this negates the point of a 3" DP as you still have a bottleneck to your flow.

    I think sports cats are a con, as you have to get them very hot to pass emissions (from my experience most of them don't) and when they don't pass (normally if you take it to a joe public MOT test station) you have wasted £££ on a "sports" cat which is illegal, and restricting flow
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  21. paultownsend
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    paultownsend Member

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    Just read your Leon thread. Superb work.
    Only from reading around on the net, but I don't think I have heard of many people failing the MOT requirements from a 200cel cat. The magnaflow's get good reviews, but mostly in the Imprezza world.

    Whst are the implications if busted by the law if running no cat? Fine? Points? Or soap on a rope for the showers?
    Last edited: Dec 23, 2013
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  22. kimhemm
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    kimhemm Member

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    I have had quite a few customer with the APR DP on the 2.0 TFSI going through MOT here in Denmark with no problems. That's with a 200 cell cat and they where doing fine and with good margin to the limit
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  23. jamiebennett81
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    jamiebennett81 Active Member

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    Thanks

    Depends on a few factors like the age of the cat. I had a 100 cell (or was it 200) and when new it would pass the MOT (although had to be made very hot)

    What are the implications...well that depends on how nice the copper is who stops you. If there is a sports cat, then the copper I doubt would ever say anything or wouldn't ever notice.

    they could give you the standard notice, for you to put a legal cat on, get it retested etc, but I can't see how they would even get to that point really, you would have to be very unlucky.
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  24. paultownsend
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    paultownsend Member

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    Well. Fitting that was fun!
    A good soak in duck oil meant no snapped studs. Extensions and wobble bars are a must.
    Getting it all bolted up was a nightmare. Had to chop down a 17mm spanner to get access.

    Well, on warm up idle it loud (using tdi straight middle and OE rear box). But once warmed up it's quite subtle. I don't think il ever upgrade the exhaust now.

    It pulls now from 2k. Harder, and revs higher. It's great. Feels noticeably quicker. Gotten by was perfect. Fits right up to theOE exhaust.

    And what I'm most please about, no cracks in my K03 exhaust side!

    Shame the rear beam brake rubber pipe burst on the way home
    #24

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