Decatting.. the myths...

[Lowe]

Did you know there's no legal requirement to have a cat fitted to car unless it's one of these 2005 complient cars?

Many, many times I hear "Your car's made after '92 therefore it's illegal not to have a cat".

False.

Yes the car will be tested at MOT to emissions levels which will probably require a cat, so you'd be daft to chuck it away, and if you were stopped for an emissions test you may fail... But for the price of a bit of pipe you can enjoy the fact your car can rev far better and won't choke up like a choked up thing.

When I had my old engine, the best mod I ever did to unleash a few ponies was ditch the cat.

[Moby-Dick]

Can you prove that ?

I'm sure the MOT Testers guide mentions it.

I'll send Jiff alng to this thread as he used to be an MOT tester

[Jiff Lemon]

Well, I stopped testing in 98 but he's how it was then....

Cars registered between 1992 (K) and 1995 (M) used to have to comply with a set of limits issued by the Ministry of transport. You had to look the car up, based on chassis number or engine number and the book told you the limits, which were set by the manufacturers.

If the car wasn't in the book (or on the PC), it had to meet with the older limits (i.e Non-cat emmissions). Cars after M reg that weren't in the book had to pass on a set of default cat limits.

I seem to remember that the rules changed recently, but I'm assuming they changed to say that virtually everything had to pass the default cat limits after a certain date.

I'll do a little fishing and find out.

[Jiff Lemon]

oh! and the rules were based on the engine - so Lowes car, even if it was a P plate, would only have to pass an emission test based on the GT turbo (non cat)

[Moby-Dick]

as you say , cars that arn't on the list as they are not manufactured in the UK ( MR2 Turbo for example ) only have to comply with a base set ( which is why philz can legally de-cat )

[Jiff Lemon]

To a point, yes.

If the car is registered after 1995 (n plate onwards) then it would still have to comply with a default set of cat limits. I'm still checking to see how the rules stand now.... They've probably tied up the loopholes by now

[Lowe]

Lemme find the link, I have it knocking around cos I'm always getting people ask me for it.

In my own case I defo don't need a cat as Jiff points out - they go on the engine rather than the car. But even newer cars don't legally have to have a cat - as long as it passes the emissions test (which I've seen several cars do cos of the lambda) you don't need the cat..

[Lowe]

Found it:

http://www.motester.co.uk/qanda.html

Q) Is it a reqirement for a car to be fitted with a catalytic converter if is was original equipment. I have a 1994 Saab turbo which is currently running with a 3" front exhaust ipe(non-cat). Provided my car can meet the emisions levels required for the age of the vehicle am I correct in assuming that the presence of the 'cat' is not a necessity? - Mike Stevens

A) There is no necessity to have a catalytic converter on any vehicle. However, your vehicle will be MOT Tested as if it had one and it is unlikely that it will pass the emissions part of the MOT without the cat. The reason being that the engine and the catalytic converter were all part of the same integral design to meet the emission requirements when the vehicle was manufactured - MOTT.

[Raz316]

How easy is it to remove? And put back for that matter
Can I assume you are allowed to remove it straight after an MOT and put it back on for the MOT (and repeat) ?

[Nox]

No Raz - ask your insurance company what they think if you're in any doubt

Nox

[Barakka]

It's true you can pass without a CAT, I know someone from another board who has a de-CAT pipe. He took the car for a service and MOT, the service was needed as it was running a bit rich and he assumed they would service it first. But they took it straight for the MOT and due to the fuelling problem it "just passed" on the third attempt at the emissions test.

Although it's true the insurance would class this as an un-authorised modification and invalidate you.

I had an occasion to speak to an Insurance assessor the other week for the company i used to be with. He tried to give me a lecture about not modifying cars because of the insurance implications and told me that they check every car with a fine comb now and catch 1-2 a month out, they had a BMW 5 series in the car park that they'd found a K&N filter on and invalidated his insurance.

[Rave]

Insurance companies are scum. All of them. Without exception. (In my experience). My filter is declared, luckily.

I used to think cats were great. Now the first thing I would do if I had a car with one is take it off. Honda can make an engine that pollutes less without a cat than with, but they're legally forced to fit them.

Rich :¬)

[schrickvr6]

my insurance company are great,i just select the power limit and i can do absolutely anything i like to the car as long as i don't go over the power limit and it is road legal

not all cars run better without a cat as they have been optimised heavily to run with one(probably gain a few bhp but lose quite a bit of torque) but a re-chip and you will get the benefits

[Moby-Dick]

likewise :-) I'm covered up to 300bhp !

[philz]

This might help