Does a decat increase the noise significantly?

[Mags]

As the title says, I've read the benefits of a decat but do they increase the noise significantly? I'm running the standard back box and I don't really want it any noisier, especially in the cabin.

Mags

[Steve_T]

Yes, definitely louder. You could look at ACTs bullet silencers if you just want to preserve your cats.

[Nigelbs1]

I put the CAT's back in mine the noise in the cabin especially at night on the motorway was insane.

[tejr]

Yes it does.. but as mentioned above, the noise I gained from the decats can be cancelled out with the slip in silencers I bought from TVR Monster iirc..

[Mags]

Thanks. Hmmm, dilemma, I want the advantages of reducing the underbonnet heat but without a huge noise increase. Maybe I'll give Tim a call at ACT and see what he says. I'm booking up a remap so whatever state its in at the remap it needs to stay at to avoid another remap!

[tejr]

To be fair, I found a lot of the noise is added when on load, although it does increase at idle a little (the note sounds much harder).. But then I had a custom exhaust made up for the car which is quieter than the sports pipes that were on there to start with.. its now quieter than the sports pipes but makes a better noise than they ever did (though it sounded a bit st before the decats)...

Heatsoak seems massively reduced too, the gearknob barely gets hot like it used to and the gear shift seems better

[Mags]

Had a chat with Tim (very nice bloke!) He said I will get a noise increase but difficult to be specific as the cats can create noise too.
I think it would be good to try and experience another Cerb with standard exhaust but de-catted, anyone in the south (preferably Surrey/Sussex/Kent direction) got this that could take me for a spin and compare?

[Gazzab]

Not worth listening to another car as the variables re systems etc are massive.
If you don't want more noise then don't decat (without sorting quieter system). Try decat and standard rear cans?
If you want lower temp then if not decat you need to sort the manifolds.

[Mags]

Gazzab said:

Not worth listening to another car as the variables re systems etc are massive.
If you don't want more noise then don't decat (without sorting quieter system). Try decat and standard rear cans?
If you want lower temp then if not decat you need to sort the manifolds.

Not sure I follow you there?
Decat and standard rear is what I am talking about (although rear box whereas you says cans?)
What do you mean by sort the manifolds? They were welded a year ago and wrapped so no expecting any issues with them.
I'm wondering how much of the 'noise' I get is just road noise, induction roar etc and nothing to do with the exhaust/cats anyway.

Mark

[scotty_d]

I am going to have a pair of silenced cans made up to reduce the heat and bring the noise down a little and just through the cats back in for the MOT.

[Gazzab]

Mags said:

Gazzab said:

Not worth listening to another car as the variables re systems etc are massive.
If you don't want more noise then don't decat (without sorting quieter system). Try decat and standard rear cans?
If you want lower temp then if not decat you need to sort the manifolds.

Not sure I follow you there?
Decat and standard rear is what I am talking about (although rear box whereas you says cans?)
What do you mean by sort the manifolds? They were welded a year ago and wrapped so no expecting any issues with them.
I'm wondering how much of the 'noise' I get is just road noise, induction roar etc and nothing to do with the exhaust/cats anyway.

Mark

OK if you have a standard exhaust then a decat wont be much louder except under full beanz acceleration and on overrun pops. So go for it.
You can get manfiolds painted in a coating that reduces under bonnet temps. Wrapping them is likely to hasten there demise.

[Phil.]

Linked de-cats reduce the noise considerably and I never had any problems with cabin noise on long journeys.

[Mags]

Phil. said:

Linked de-cats reduce the noise considerably and I never had any problems with cabin noise on long journeys.

Interesting, where did you get those or are they home-made?

[FUBAR]

Id happily take you for a spin Mark, but I've got ACT's Big Bore system as well as decatted, and I'm running 888s (now that's a noisy tyre for you!). Having said that, TBH, I must be going deaf in my old age because I've done a few inter Continental trips and never thought the noise was unbearable.

[Rawhide]

I have a 4.5 with ACT decats, ACT manifolds as well, standard rear box. I have to say that the noise is significantly louder under load. I'm not keen on the sound either. Outside the car at idle it sounds a bit deeper but it's not worth the noise and drone for me.

That said I've not put many miles on to really evaluate but as I plan to track the car I'm thinking of removing them soon.

Edited by Rawhide on Monday 23 January 15:06

[Mags]

Fubar, As I know you are Horsham way I wouldn't mind a quick spin if possible. I've only ever been in about 3 Cerbs before I bought mine so I can't say I remember much about the difference in noise.
I'll ping you via PM.

[Gazzab]

I would suggest comparisons to other cars where induction, exhaust, engine, mainfolds etc might be different wont give you a comparable test.
The received wisdom is that standard exhaust and standard manifolds but with decat is a good thing and not too loud. Just a bit louder. Some linked decats will reduce it further.

[Mags]

Yep, I'm thinking the decat sounds like a good idea now, I'm assuming its just bolt-in, no cutting etc assuming I've got standard 4.2 cats & system.

[SL500]

Yes is the answer. Mine is sports and decatted. Bloody loud and flames!! Hmmmm.....

[FUBAR]

SL500 said:

Bloody loud and flames!! Hmmmm.....

You make that sound like its a bad thing