De - De cat

[RichV6]

As the title states - thinking of replacing the decat pipes with the real thing. Have run without for four years now but recently have got a little tired of the fumes and everything in the boot stinking of unburnt fuel.

Anyone any hints or tips, high flow cats over standard, and or the difference they make? Car currently running ACT manifolds and big bore "quiet" system with no cracks or gas leaks.

[tur8o]

i recently fitted some act silencers in place of my cats/decats. i dont think it will stop the fumes much though, ive had cats, decats and these and not much difference in fumes etc. biggest differences are heat and noise.

[Gazzab]

I ran a cerb with cats for a while - it wasnt at all fumey.

The de-cat certainly makes for smellyness, particularly in the boot (although I tend not to spend much time in there).

Re-catting will change the noise, takes away the raspiness at 3K plus, it will also remove flames and much popping and cracking.

A re-cat with sports exhaust is pretty good still - ie a nice enough noise.

Personally I have no experience of sports cats but I would just stick OE ones in.

[touching cloth]

Running rich is a Cerb trait, makes for the fuelly smell (but also makes for flames and pops as said). Sadly that trait will kill cats in quite short order which is a reason why so many run decatted - it's not only a cheaper fix but pretty much a fix once solution (at least ignoring the mot issue it is). Faced with cat replacement every couple of years I'd rather live with a bit of pong.

[FUBAR]

Mrs Cloth has just got used to it after all these years

[RichV6]

Waiting for a call back from a certain gent at raceproved. I'm hoping a tweak in the mapping may be in order as the stink is much worse since fitting the new exhaust a few weeks back, as for the noise and the flames but for those behind its none too pleasant.

FWIW measured 114db properly and 131db 3 metres from a brick wall so need a little help to get back on a track.

[FUBAR]

RichV6 said:

FWIW measured 114db properly and 131db 3 metres from a brick wall so need a little help to get back on a track.

I know some of you think that that certain person at Raceproved can walk on water, but he will need to enlist the help of the big boss upstairs to get your car on track with those outputs

[Marpug]

I've been up and down the options.

Single silencer sports + CATs
Single silencer sport exhaust + Decats = Ear bleeding! but regularly set every parked cars alarm off when I passed it.
ACT sports + standard decat pipes =
ACT sports + Silenced decat pipes
ACT sports + CATs

Currently on the later and haven't really noted much differance in pops/crackles and noise to the decat options, IMHO it has about the right balance of less fumes, enough noise to keep smiles and comfortable to put up with on a long run.

Keep meaning to get a noise check as it still seems loud enough not to make a track day....

[PaulK]

Linked D-Cat pipes and sports exhaust + tunnel I have heard the standard CATS are very free flow so do not cause to much of a restriction so just stick with them.

[itiejim]

Cats or no Cats there should be no stink!

It's an indication of either a very poor mixture or a leaky exhaust - both of which really needs sorting.

Mine runs a linked de-cat with no smelliness either inside or in the boot. It was the same when I had the cats in.

[PaulK]

itiejim said:

Cats or no Cats there should be no stink!

It's an indication of either a very poor mixture or a leaky exhaust - both of which really needs sorting.

Mine runs a linked de-cat with no smelliness either inside or in the boot. It was the same when I had the cats in.

I have always had fumes in the car after a couple of hours get a bit of a headache. Never noticed the smell in the boot, the heat yes but no smell. Unless I have been overcome with the fumes from the cabin and not noticed. I even had these after a full tune by Jools and I do not think the exhaust is leaking so I am a bit lost to what it could be (they are all like this sir) maybe?

[Gazzab]

Well all of mine have done this smelly thning with cats removed, they have continued to do it after engine rebuilds, re-maps, services, exhaust changes, MOT's etc.... Maybe I have an acute sense of smell (better than acute angina).

[RichV6]

The problem with refitting the cats is I only have one original and one cheap aftermarket which I used for a couple of MOT'S. So do I go high flow cats, stump up for one new geniune unit, or stay decatted.
Theres no leaks throughout the length of the system as I fitted and re adjusted everything myself. Might have to live with the smell, or should I say those following might have too.

[Ireland]

The original cats were 200-cell and this is the type you need if you plan to run with them fitted full time.

Many of the ones on ebay are 400-cell and are only suitable for fitting while on the way to the MOT centre and back again.

The comapnies advertising on ebay, etc will make up 200-cell ones for you but they are very expensive.

The car will run and feel hotter with cats fitted.