making a de-cat! help!

[L9 GOW]

hey peeps!
i know there is already a couple of threads about de-cats but this one has got a bit of a twist!
i just picked up a spare cat for my cupra and was looking to cut out the cat and just weld a bit of pipe in!
can anyone tell me if this is a good idea or bad idea?
will it bring on any engine lights?
will it sound good? it already has a miltech cat back system!
has anyone done this before?
thanks in advance

 

[Reuvers]

I really do not see the point.

Even if you replace the centre section for a straight pipe, then you still have to cope with the biggest problem which is the bend. Its tiny!

So you could opt replacing that too, but in all fairness, then you've practically made an entire new downpipe.

ANother thing to think about when doing this, is what are you going to do with MOT? You won't pass with a decat.

If you want a decat get one for +- 100 quid, which is at least 2.5" all the way through. That way you can stick your OEM cat back for MOT

 

[dai cupra]

sounds good reuvers have u got one done and did u see a difrence with 2.5 inch decat:

 

[L9 GOW]

making it isnt the problem and neither is the mot as i will be keeping my original cat for that!
was just trying to make sure i wouldn't have problems with engine lights and wanted to know what it would sound like!
as for the £100 for a de cat would rather spend it on something else for it!
thanks for your comments and you have very valid points

 

[Myki da Pyki]

I take it you've got weld on flanges to mount the 2 lambda's then?

 

[jam666999]

Im assuming hes got two standard downpipe and cats, and is going to remove the cat on one and just replace with some pipe. You will more than likely get EML lights unless you space the 2nd lambda or get it mapped out. You wont see any gains from this really as the standard downpipe is a big bottle neck in the system. Better off waiting and gettin an uprated one.

 

[L9 GOW]

yeah i have got two cats!
one is on the car and the other is spare!
i am going to have a look at it today and check bore sizes etc etc.
if it works and i get good gain from it and a nice note from it then good result,
if not then it will only cost me my time and i will have to bite the bullet and buy a de-cat

 

[Fl@pper]

cut it from around the top if you do - less likely to look as obvious for tampering if you are keeping the shell itself intact

 

[Myki da Pyki]

You'l end up paying more making one than buying one anyway.

£80 on ebay an your sorted

 

[Reuvers]

again, I find this a very stupid idea.
Like I said, its not so much the inside of the cat which is the problem. Its where it bends upwards to meet the turbo.
If you have one spare surely you have noticed this? If not go have another look.

As myki said, 80 quid and you're sorted without all this DIY which in the end will not give you better results as you mentioned a few posts back.


tbh this sounds a lot like the cheap modding people do on escorts and mazda's by sticking a broomstick through the silencers to get that 'racy' sound PMSL!

 

[L9 GOW]

i think i better have a better look at it!

 

[Reuvers]

lol

 

[L9 GOW]

reuvers did you get a good result from a de-cat?
and how does it sound?
dont want it sounding like there is a 1.1 saxo with a cherry bomb on it away to go past

 

[jam666999]

You dont really get that cheey bomb effect with it being a turbo, you'll get a fairly good gain from an uprated downpipe and decat.

 

[Reuvers]

agreed as said above.

I still have the middle and rear silencer, and they do their work (2.5" all the way that is)

gains I am not sure about as I still run standard boost/map

I guess I'll find out in a couple of months what all my goodies together will produce

 

[AlexGSi2000]

Know this wont help out, but a mate of mine de-catted his by knocking through all the catalyst material with a screwdriver and a hammer!

 

[Adam R]

Know this wont help out, but a mate of mine de-catted his by knocking through all the catalyst material with a screwdriver and a hammer!

the title .. 'chav' and 'ghetto' come to mind

 

[AlexGSi2000]

the title .. 'chav' and 'ghetto' come to mind

lol, can see where your coming from.

Was on his passat 1.8t, the cat had collapsed, and being a student he didnt really have the cash for a new one, so we improvised.

 

[Adam R]

i suppose that is a good bodge...