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centre section decat? or not, hmmm

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Old 25 November 2009, 08:24 AM
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fent
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Default centre section decat? or not, hmmm

I have a 2003 WRX blob which has the standard exhaust sections on with the exception of a racebox back box. the racebox is nice but I have now got used to it and want a little more sound from it. I have heard that removing the centre section will help, is this true. As the back box is pretty new (on when i bought the car) I don't want to change this so will I get much difference by just changing the centre section?

I am not doing this for power gains, just sound. It is my everyday car and covers some mileage so I need to keep the economy to a sensible level...

Although as remap would be nice...

... but new bathroom must come first, DOH.
Old 25 November 2009, 08:54 AM
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H2o-uk
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Hi, I have a de resonated rear pipe on my 03 WRX this helps with the sound a little. The centre pipe has a cat in it so would help with performance if you replaced it with a decat pipe and also make it louder again.

Old 25 November 2009, 09:05 AM
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The Newage cars only have two cat's. One in the turbo up pipe and one in the turbo down pipe. The centre section is a resonator.

Remove it for sound and better flow.
Old 25 November 2009, 09:37 AM
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baz995
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The new age has 3 cats

http://www.scoobypedia.co.uk/uploads...ust-system.gif

but blue is right in saying the center section is just a resonator so should be fine in swapping out, shame you dont want a decat or sports cat as the difference is amazing
Old 25 November 2009, 09:44 AM
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mattchew
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both wrong lol there is no cat in the uppipe

the new age has 2 cats, one in the down pipe and one in the pipe that connetcs from down pipe to center puipe it goes as below

turbo down pipe with cat
then pipe connetcs from cat to centre pipe and has cat
resonated centre pipe
back box
Old 25 November 2009, 10:03 AM
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If you look at the picture I added, it shows three cats on a new age WRX,

Pre Cat in Up Pipe
Down Pipe with Cat
Centre Pipe with Cat <--- usually replaced with a Decat on WRX PPP
Rear Pipe with resonator

Sometimes some people class the downpipe as one peice when it is two peices with two cats , down pipe and centre pipe.

I'm new , but I've asked LOTS of silly questions about this recently trying to understand myself.
Old 25 November 2009, 10:15 AM
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Originally Posted by mattchew
both wrong lol there is no cat in the uppipe

the new age has 2 cats, one in the down pipe and one in the pipe that connetcs from down pipe to center puipe it goes as below

turbo down pipe with cat
then pipe connetcs from cat to centre pipe and has cat
resonated centre pipe
back box
just changed all of mine mate and there is definately a cat in the up pipe, downpipe and mid pipe

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Old 25 November 2009, 12:23 PM
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Mike1609
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The number of cats depends on the MY of the car.

MY03-05 WRX's (2.0) do have 3 cats - uppipe / downpipe & centre as per the picture. (N.B. STi's of this year only have downpipe & centre cats)

MY06 WRX's (2.5) only have 2 - downpipe & centre.

Thats as i understand it anyway.

Mike
Old 25 November 2009, 12:53 PM
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H20 Uk,

cheers for the diagram, I think I may need to check my understanding of what I am going to replace. I saw a centre section pipe advertised on scooby world and assumed this was the section just before the backbox although this is called the rear exhaust pipe and resornator according to diagram from H20 UK. It looks the same so I'll just double check before ordering.
Old 25 November 2009, 02:18 PM
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mattchew
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Originally Posted by baz995
just changed all of mine mate and there is definately a cat in the up pipe, downpipe and mid pipe
then you dont have a wrx not sti?

the 03 sti has 2 cats one in the downpipe and one in the middle pipe before the centre section

feny if you want a un-resonated pipe that goes from backbox to 2nd cat then this is the part you need

http://www.scoobyworld.co.uk/catalog...roducts_id=448

that will match up to your standard 2nd cat

Last edited by mattchew; 25 November 2009 at 02:23 PM.
Old 25 November 2009, 04:14 PM
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Yep i have the same as Fent 2003 WRX Blob, cat in uppipe and all others as my post above
Old 25 November 2009, 04:16 PM
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from scoobyworld:

On 2001-2005 WRX 2.0 cars there is a small cat in the 'Uppipe' (pipe going to Turbo), this needs removing to avoid it overheating after mapping and damaging turbo. On some cars this may have been done already, if not we can provide this service (see drop down options)
Old 26 November 2009, 11:28 PM
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Mattchew,
Yes the link you added is the part I was originally looking at. I think the confusion is that they refer to it as the centre section but others call this the rear exhaust pipe. The diagram refers to centre exhaust rear pipe or midpipe.

Anyway, looks like the centre section pipe from scoobyworld to remove the resonatr is what I want (for now anyway)

Cheers

Fent
Old 20 February 2012, 12:41 PM
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Originally Posted by mattchew
both wrong lol there is no cat in the uppipe

the new age has 2 cats, one in the down pipe and one in the pipe that connetcs from down pipe to center puipe it goes as below

turbo down pipe with cat
then pipe connetcs from cat to centre pipe and has cat
resonated centre pipe
back box
OP states he has a WRX not an STI wich has 3 cats, the STI has no cat in the up-pipe..the WRX does.. both cars have one in the down-pipe and one behind that (replaced with a PPP kit), Centre is a resonator as stated above by others.
Old 23 August 2016, 03:39 PM
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chris wheela
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Originally Posted by baz995
just changed all of mine mate and there is definately a cat in the up pipe, downpipe and mid pipe
Does any body know where I can buy a center cat pipe?? Sports or standard?
Old 23 August 2016, 06:45 PM
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Don Clark
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Originally Posted by chris wheela
Does any body know where I can buy a center cat pipe?? Sports or standard?

Still life in this old thread

As terminology can differ from that used by Subaru.

What are you trying to replace and with what??

Sports cat normally fits in the down pipe section, although some have a catted replacement mid pipe section for MOT use with a normally decatted turbo back system.

Diagram below uses Subaru's terminology and is for UK 2.0L WRX Newage cars

Old 23 August 2016, 10:34 PM
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chris wheela
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Originally Posted by Don Clark
Still life in this old thread

As terminology can differ from that used by Subaru.

What are you trying to replace and with what??

Sports cat normally fits in the down pipe section, although some have a catted replacement mid pipe section for MOT use with a normally decatted turbo back system.

Diagram below uses Subaru's terminology and is for UK 2.0L WRX Newage cars

Cheers for the reply, basically what is labelled number 1 in this diagram is what I need, as its blowing and making a horrid noise . I need to order one or buy one near Birmingham, but every time I search for "midpipe" "centre cat" It comes up short and I can't find it at all. Need one ASAP. Please help
Old 24 August 2016, 04:08 AM
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Most aftermarket exhausts come with an extended downpipe which replaces the standard downpipe and midpipe, meeting with the centre pipe.

Edit :- Most people refer to the 'rear exhaust pipe' shown above as the center pipe..

Last edited by Kaeo; 24 August 2016 at 04:09 AM.
Old 24 August 2016, 07:18 AM
  #19  
Don Clark
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You are probably better off purchasing a 2nd cat delete pipe (same as PPP) as the cheapest answer. (remap not immediately necessary, although would improve the performance. It will still pass an MOT without the 2nd cat)

http://www.ebay.co.uk/itm/Scorpion-D...FtXfv5t1-i6htQ

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