johnski

Which is the main cat classed as on a 2001 wrx?
Apparently if I leave this one in I can
Decat the rest and still pass MOT

tubbytommy

iTrader: (20)

the second/main cat is in the downpipe just after the turbo, the first cat that you can remove is in the uppipe, just replace this with an sti uppipe

MattyB1983

iTrader: (51)

You have a cat in the up pipe and one in the downpipe.
Remove the up pipe and fit an sti one and then remove the restrictive downpipe and fit a sports cat downpipe.
Will still pass mot but free up a few more ponies.

johnski

Thankyou this is helpful iv already got a decat up pipe ( h+s) a decat centre
Section and afterburner rear silencer, so if I did go for
The sports cat down pipe would it still pass ?

tubbytommy

iTrader: (20)

if you have a decat centre section then you have no cats so no it wont.

to pass you need decat up pipe and sports cat in downpipe then it will pass or chuck the lot out and go full decat,get it mapped and find a scooby friendly mot man.

johnski

At the moment iv still got one cat Cus I havnt changed
The down pipe yet, and my mot due in a few days? So it won't
Pass with just that then? So what is the cat pipe? Hasn't that got a cat in it?

tubbytommy

iTrader: (20)

it will only pass with the downpipe cat in place, if you want it to pass you need the downpipe one, it wont pass with just the uppipe one.

johnski

Oh that's good then cheers! Well at least I know it will pass. Once
Iv got mot out of way I will decat down pipe then I will have full decat system! Or do I need to get rid of the cat pipe too? That's the pipe between the down pipe and centre pipe ain't it? What does that pipe do then?

darrenb87

iTrader: (1)

I think you might be getting confused about different sections of the exhaust system.
It might be best to list out the parts you have replaced on your car.

tubbytommy

iTrader: (20)

jesus you are confussed you have more cats than an old lady

Jacko4130

iTrader: (3)

Decat the lot and drop your tester £20...... Simples

johnski

Cheers Darren! Ok iv replaced up pipe to a decat one, iv replaced centre pipe with a decat centre one and iv replaced my small backbox with an afterburner rear silencer so far

johnski

Lol cheers guys, I'm still learning ,

darrenb87

iTrader: (1)

The centre cat that you keep saying is just a centre section to quieten down the noise but isn't an actual cat so won't effect the mot or emissions.
You have removed the pre cat so far so you have the second cat to go from what I can make out from your description. Go through your mot with that in place then de cat it after that.

Don Clark

A picture is far more helpful...............

johnski

Ok cheers

MattyB1983

iTrader: (51)

The diagram is wrong, there are only 2 cats.

The up pipe has a cat in.
Downpipe has a cat in.
Middle section has a resonator box.
Then the rear box.

You have already replaced the up pipe so that's sorted.
You have also replaced the middle section to remove the resonator so thats sorted.
Now you are left with a standard downpipe which has a cat in place. I would suggest swapping this for a sports cat downpipe. This will still allow you to pass an mot but will be much more free flowing.
An open sourse map would also be on my must list if I was you.

Your other option is to get a de cat downpipe. However you would need a friendly mot tester or swap it every year.

Don Clark

The diagram is correct for UK newage impreza (4 piece exhaust).


Classics are different.(3 piece exhaust) and they don't have a pre-cat in the up pipe.

The resonator in a classic mid pipe can sometimes be a cat (depends on destination)

jazzyjembreaze

iTrader: (11)

Iv just passed a cat up a tree if any 1 has lost one

johnski

So iv still got the down pipe to decat and the mid pipe to do. Then a remap.

tubbytommy

iTrader: (20)

read mattys post

Emmaroids

iTrader: (2)

what about this cat?

Midlife......

iTrader: (2)

Could have sworn the UK Bug WRX had 3 cats.........

http://www.wallpaperinstaller.com/scooby/mattspec.gif

Or am I thinking about the yank job?

Wish my memory was better LOL

Shaun

tubbytommy

iTrader: (20)

just order yourself a turbo back decat system, job done.
making an exhaust from bits is likely to not fit anyway.

johnski

I think I will do that tubbytommy saves messing about
Cheers