De Cat

[wildrnes]

how do i do it

will it make mugh difference

is it easy to put back ?

[Usually007]

I asked this a while back and didn't get a response either.

I think there are actually 3 cats (could be wrong); a pre cat on the manifold, one under the driver and possibly the rear box.

Anyway my local exhaust specialist wants to remove the cats as he keeps saying "It'll fly without them" however nobody seems to be doing it and so I am a little wary.

He reckons he would put the Lambda sensors back in position but I am not sure they would show the right readings if there were no cat in between them.

Also not keen on having to struggle to put the cats back in again for the MOT if they were required to pass the emmissions test.

Some guys at the Gaydon meet reckoned you could get a "free flow" performance cat but again nobody, as far as I am aware, has had this done!

What we need is a techie to answer these concerns and explain it.

Anyone care to comment

[TonyGoose]

Downpipes (or manifold / header if you prefer) is 6 pipes into 2 into 1 ...

There's a pre-cat in each of the '2' pipes ...

Look down the exhaust side of your engine and you'll see the bulges.

And there's the main cat in the exhaust mid section under the car.

To gut the pre-cats, you need to cut open the pipes...

Unless they're already knackered in which case it's just about possible without.

Only know this coz i saw it done on somebody's IS

Be aware you'll almost certainly fail an MOT test if you remove / gut the main cat.

[Monster-Mat]

that is true...........

however the pre cats are superflouros, and dont make much difference to an MOT reading, if any as there only to assist in emmisions till the main cat has heated up.

you can get the main cat replaced with a piece of pipe, but the lambda sensor will still have to go in.

the lambda sensors measure the content of the gas after the pre cats( then make adjustments) the read the mixture again after the main cat.

removing the cats on the is200 WILL release more HP.

the precats are known to breakup anyway, its a fault in manufacture, mine did after 7000 miles

[Usually007]

So Mat are you saying that you could remove all the CAT's, keep the Lambda sensors in place and the car would still run okay AND pass an MOT?????

[Kavey]

So Mat are you saying that you could remove all the CAT's, keep the Lambda sensors in place and the car would still run okay AND pass an MOT?????

Remove all the CATs and I'd say you'd very likely fail MOT due to emissions.

[Zee007]

Remove all the CATs and I'd say you'd very likely fail MOT due to emissions.

I agree.... best bet is to have a middle pipe made (and accomodate the lambda sensor) then swap it back over for the MOT. I don't think the two pre-cats would would be an issue...