How loud is a Cerb on standard exhaust and Cats?

[crazymatelot]

My Cerb 4.2 is fitted with a sports exhaust and cats. It is quite loud. I'm told I can be heard coming home from about a quarter of a mile away. If I was to try and bring the noise level down, by fitting standard boxes, how much quieter would it be? Would it be worth the effort and expense?

[JensenA]

Yes it would - Standard back box with de-cats gives a great sound. Not noisy, but has a sound like you know it means business, and it gives a really good, angry 'bark' when you floor it, and plenty of pops 'n bangs on the overun.

[crazymatelot]

Okay, what exactly are de-cats? does this entail removing the cats completely?

[SimonKD]

Hi dave

Another thumbs up for standard exhaust and de-cats although the standard exhausts may prove hard to find either second hand in good condition or brand new.
On the de-cat front you can have seperate de-cat pipes that bolt in where the cats are at present or linked de-cat pipes which bolt in the same or even keep the standard cat pipes and have the catalyser material removed from them.

Regards
Simon

[crazymatelot]

Thanks for the explanation Simon, after two years the noise on a long run is begining to do my head in. After four hours it can be a bit much. What I am looking for is to quieten the car down a bit, it still needs to sound like a Cerb but i don't want to strangle it, and of course it needs to be able to pass an MOT without messing about replacing bits of exhaust come MOT time.

[SimonKD]

I changed from Blue Flame sports pipes with cats intact to standard exhaust pipes and cats removed for the very same reason, the noise on long runs. I get the best of both worlds, reasonably quiet(ish) at low revs but a decent bark when opened up a little.
If you do remove the cats you may or may not need a decat TVR friendly garage come MOT time. I've had 3 MOT's post decat and never a problem. As I said though locating a standard backbox/tailpipe assembly may be a problem.

Regards
Simon

[clive f]

if you want it quieter then fit a standard rear silencer, Joo and I did a lot of testing on this last autumn, and the standard rear silencer does a fantastic job.

[JensenA]

Douglas Valley or Bell Hill are a good source for used rear silencers - about the £200 mark IIRC.

[crazymatelot]

I think I would be prepared to pay almost anything to make long trips more enjoyable if that is possible in a Cerb. Would that be about £200 per side or total?

[clive f]

total, ita one big silencer across the back of the car

[crazymatelot]

Cheers for the info lads, think I've got all I need now.

[Byker28i]

The other option is the quiet exhaust from ACT with decat. 106db on my car, or 96db when the cats are in for the MOT (measured at 50cm from the tailpipes 45 degree angle). Decat is nice, throaty, plenty of pops and bangs, with the cats in sounds very quiet.

Inside it's reasonable quiet, easy enough to have a conversation at motorway speeds, and without the cats it's a much more pleasent cabin in the summer.

Another added advantage is that the ACT exhaust is a lot lighter and smaller, so you have a huge improved road clearence at the rear.

[Ireland]

I've tried all options and standard back-box with de-cat is the best compromise for comfort in the car / sound outside / performance.

I have a full standard exhaust on mine at the moment and it's costing me 10mph on the straights in Mondello on track days but I fitted it for the NCT (Irish version of the MOT).

I'll be going back to de-cat soon.

[amazon]

I have just removed Sports Pipes (from my 4.2) and fitted a 4.5 back box and no cats. Tested at Snetterton at 5,250 revs at 101dB.

Car still sounds great and pops and bangs merrily. Much smoother to drive as well.

[grahamn]

Mine is 97 - 98db with standard box and cats, just what I need to get onto any trackday with no issues. Is a bit quite though compared to other Cerbs.

[Byker28i]

grahamn said:

Mine is 97 - 98db with standard box and cats, just what I need to get onto any trackday with no issues. Is a bit quite though compared to other Cerbs.

I thought you went for the SP system but with Cats to keep the noise doen to trackday limits?

[dempsey]

I've got a Silverstone Performance back box with decat pipes and it makes about 101db. On the motorway with just a crack of throttle (all you need at 85mph) conversation is easy - when you open up it's loud but in an angry way not just noise for the sake of it.

[grahamn]

Byker28i said:

grahamn said:

Mine is 97 - 98db with standard box and cats, just what I need to get onto any trackday with no issues. Is a bit quite though compared to other Cerbs.

I thought you went for the SP system but with Cats to keep the noise doen to trackday limits?

Hi Dave I did and it still measures about the same. I quoted what mine was with the standard set up as that is what he asked about.

[mikeinsheffield]

Or you could go for the logical alternative - put cats on and keep the sports back box.

Mine is an 02 4.2, sports back box and just had Joo replace the cats (old ones were collapsing, rattling, and restricting flow and power). On Joo's advice I went for replacement cats, as I frequently have young kids in the back, and he advised that Cerbs have a low pressure spot that can draw fumes into the cabin through the side windows. Not too bad if it was just me, but didn't want to subject the kids to noxious fumes (too much).

Not sure what decibels mine is, but it's definitely got the right "cerb" noise; it's reasonable at low revs and when pottling in traffic, but is definitely loud enough for my missus to know when I'm driving home up our road . When pressing on, it's got a great soundtrack, and has a great succession of pops and crackles coming down the revs from 4k - 3k!

Personally, I love it. It's loud enough to be distinctive, easily discernable above other traffic noise, sounds fantastic when trashing it hard, and yet not tooooo bad for when you don't want it to be too loud and driving gently.

[FUBAR]

Well, at the Brands TD today the sound tester just looked at me and shook his head after the first attempt(ACT Big Bore sports pipes and decat) . 109dba @ 3750rpm ("honest mate, that's 3/4 of the rev range" )

Stuck the ACT track silencers on, down to 95.5dba

I dont have a problem with the level of noise at cruising speed with the sports pipes. Maybe Im already deaf?