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After the sucess of the removing the egr by placing the blanking plates in place, i am enjoying the better fuel economy. But apparently the decat is more dramatic at reducing fuel usage. So here is a picture of the exhaust i removed from the breaker car:

the front section seems to be in shite:


but the cat is ok:


would it make sense to cut the cat out of this, beat the shite out of it then weld it into my own exhaust system keeping the cat in my car just incase.
Has anyone ever done a decat. Is this the way to go about doing it?

I did mine & honestly wish I hadn't. Absolutely no benefit, slightly more noise, definetly more smoke and it smells like a good old-fashioned diesel.

Dont bother.

the de egr definatley worked. I thought jamjar said the decat would be even better.
Are you saying this about your 2.2 hdi, perhaps the 2.0 is different.

The turbo definately spools up quicker on mine, but I have to qualify that by saying it had the powerflow and decat at the same time

As the cat & fap share a common housing on a 2.2 and it separates between them, I could clearly see the cat element. It was a ceramic block, about 5" diameter by 3", with about 200 odd straight passages through it, of maybe 1 mm diameter. On the outlet end, there was a fine metal screen of interwoven wire construction.

I examined it while replacing the flexi section of the exhaust - you could clearly see through each passage and it was obviously perfectly clear. I bashed it out anyway, thinking it probably represented a significant flow restriction even 'as new', but TBH I could tell any difference.


This is the assembly on the car.

This is the inlet end of the fap, but the cat looked similar except you could see through the holes.

complete assy, cat's inside 11, fap's inside 12

Granted my 2.2 is different....

My previous HDi 90 Xsara, had the cat replaced at about 80k to cure low power / poor response and when I got rid of it at 185k, I think it needed doing again, (or decatting). It had more turbo lag and exhaust smelt more like an non-cat diesel. If your car is getting like this, you may get a benefit, but if it's working OK, I doubt you'll notice.

May be complete coincidence, but since I decatted mine, the engine 'wobbles' at tickover, like you have a dodgy mounting, (which it hasn't). I get a lot more smoke if I use all the power and no apparent benefit. This all makes me wish I hadn't bothered.

i think you'll find that because the turbo spools up quicker that you dont have to hold your foot down as long. it is a flow restriction and thus shouldnt be there but the tossers in the eu think its a good idea to have one.

look in to diesel tuning further you'll see what i mean, because if it doesnt do anything else apart from spool the turbo up quicker then why waste money on custom systems for diesels.

turbo diesel owners club uk will tell you the same stuff i have.