The Noise Conundrum!

[firewallguy]

Now, 99% of the time I love the noise my Cerbera makes; a deep rumble at tickover, demented buzzsaw at full chat, and the inevitable artillery barrage on the overrun. Perfect for the 60 mile round-trip cross country blast to work once a week during the warmer months.
But on a longer journey, at "normal" motorway speeds, it's a boomy, headache-inducing PITA. I took a trip down to the Sunday Service at Silverstone from Telford at the weekend at it was hard work, and I felt sorry for my 5 year old lad that always comes along with me to these events, we can only communicate via hand signals until we leave the motorway!

Now I know that there are quieter exhaust systems available. I bumped into another Cerbera and owner at Oulton Park last month, and he had the Silverstone Performance exhaust with linked decat fitted to his. I just scraped through the noise test at bang on 105dB with Decibel Devils up both pipes, whereas he sailed through at 101dB with no additional silencing.
The thing is, I spent some time watching from the pit straight whilst he was on track, and it just sounded too quiet to me, still nice but missing that head-turning soundtrack.

I just wonder if there's a way to lose the in-car boominess at 3 to 4 thousand revs, but keep most of the drama when pushing on. My Cerb's got a custom decat stainless system with single silencer/backbox per side with over-size 3.5 inch tailpipes.

Would it be worth trying to replace the silencers for ones with more baffles and standard size tailpipes? Also mine doesn't have the x-connected decats and I've heard that can reduce the noise to some degree?


Edited to show the correct 'quiet' exhaust system.

Edited by firewallguy on Wednesday 22 October 22:15

[QBee]

Would the Decibel Devils take the edge off it for longer trips?

[purpleliability]

I just bolt the ACT track cans on for long journeys. It's only a pair of micalor clamps to remove them and put the sports tails back on. Makes a MASSIVE difference on long journeys.

[NilsP]

why not put something together with electric axhaust valves?
Maybe you can open up the back box, weld in a 'bypass pipe' and install the electric valve.
That way if you want a bit less noise, it's just a flick of the switch

[firewallguy]

I drove back from an Anglesey track day last year with the Devils left in, and they didn't make much difference to be honest.

The bypass valve thing is certainly something I've thought about but it's beyond my limited mechanical ability I'm afraid.

I have some bolt on ACT trackday silencers, which fit over the existing tailpipes, so not really useable on the road due to how much they stick out. I suppose I could look at getting the exhaust modified to allow the tailpipes to be swapped for silencers like purpleliabilitie's, although I'd have to replace the ones I've got as they are designed to fit over the 3.5 inch tailpipes.

[NilsP]

Well if you don't think you can do it yourself
Any custom exhaust shop would be happy to do it for you.
Not that big of a job.
You need something like this (sorry for my Paint "skills")

[ukkid35]

I'm probably between 105 and 106, depending on weather/surroundings/tester etc. with the Silverstone Performance back box and linked decats I fitted earlier this year, so the only tracks I've been to recently are Anglesey and The Ring. I also went to Zolder but was black flagged within ten minutes despite short shifting at 3500.

The SP box is a massive improvement on Sports Tails with cats, no more booming on the E40/E42. Headaches are now due to traffic instead.

My new plan is to try a pair of these, just $55 each



http://www.summitracing.com/int/parts/cci-3di35l/o...

Because the 3.5" tailpipes were a bit banged up (box was from our favourite salvage dealer), I had to use a pipe expander, without it I wouldn't have been able to smooth the dents in the tail pipes, allowing the removable inserts to fit.







That should shave off 2 or 3dB, enough to get me under 105, hopefully I'll find out on a track day soon.

As a pair they are rated to 500bhp, so hopefully no loss in performance either, unlike the ACT track day cans I used to fit to the Sports Tails which would strangle the engine.

[OutlawFlat4]

I think Aston's have a control that allows different exhaust tones/levels.

[Martyn-123]

Hi,

Similiar problems on long journeys which can make the trip tiring so went for the simple option of a set of musicians earplugs, simple but effective (and probably cheaper too)


Martyn....

[Mags]

NilsP said:

why not put something together with electric axhaust valves?
Maybe you can open up the back box, weld in a 'bypass pipe' and install the electric valve.
That way if you want a bit less noise, it's just a flick of the switch

Aren't these used in modern cars now to keep them quiet at low RPM, I seem to recall BMW/Jaguar/Aston have something like this.
I know hot rodders use them, a quick Google showed up this:
http://image.popularhotrodding.com/f/hotnews/1007p...

[NilsP]

Mags said:

Aren't these used in modern cars now to keep them quiet at low RPM, I seem to recall BMW/Jaguar/Aston have something like this.
I know hot rodders use them, a quick Google showed up this:
http://image.popularhotrodding.com/f/hotnews/1007p...

Yes indeed the F-type V8 and corvette use valves like that
No performance loss if properly done

[a1rak]

NilsP said:

Mags said:

Aren't these used in modern cars now to keep them quiet at low RPM, I seem to recall BMW/Jaguar/Aston have something like this.
I know hot rodders use them, a quick Google showed up this:
http://image.popularhotrodding.com/f/hotnews/1007p...

Yes indeed the F-type V8 and corvette use valves like that
No performance loss if properly done

I've got the latest 6 silencer quiet ACT system and it comes in at just under 100db with no CAT's so is perfect for track days. It is expensive but still has a really nice sound and makes long journeys a pleasure. Sticking any restriction up the exhaust will cause a power loss or worse as it can badly effect the fuelling and damage your engine.

The problem with the bypass pipes will be room. If you are going to keep large bore pipes for sound and power you need a massive amount of space to fit in enough silencers and then on top of that you need the bypass pipework ....I just don't think it will ever fit. You will have to use small bore pipe which would negate the need for a bypass system.

I would go the ACT route, I'm glad I did and so are my neighbours

[purpleliability]

This is the full ACT system with and without the bolt on track silencers. You only lose 5% at the top end but the mid range torque does take a hit.

[firewallguy]

Hi All,

The owner of the 'quieter' Cerb from Oulton Park has been in touch to point out an inaccuracy in my initial post:

"Just a quick clarification: my car has a Silverstone Performance exhaust with linked decat (not an ACT piece)."

Apologies for that.

[Byker28i]

firewallguy said:

Hi All,

The owner of the 'quieter' Cerb from Oulton Park has been in touch to point out an inaccuracy in my initial post:

"Just a quick clarification: my car has a Silverstone Performance exhaust with linked decat (not an ACT piece)."

Apologies for that.

Did he have cats in?

[ukkid35]

purpleliability said:

This is the full ACT system with and without the bolt on track silencers. You only lose 5% at the top end but the mid range torque does take a hit.

That's good of Joolz to do a side by side comparison for you!

I may go see Charlie at SRR and ask for a side by side as well, but not until I've done my valve clearances.

[OutlawFlat4]

Mags said:

Aren't these used in modern cars now to keep them quiet at low RPM, I seem to recall BMW/Jaguar/Aston have something like this.
I know hot rodders use them, a quick Google showed up this:
http://image.popularhotrodding.com/f/hotnews/1007p...

This looks really interesting. Would it fit the ACT sport exhaust or would it need modifying?

[ukkid35]

firewallguy said:

Hi All,

The owner of the 'quieter' Cerb from Oulton Park has been in touch to point out an inaccuracy in my initial post:

"Just a quick clarification: my car has a Silverstone Performance exhaust with linked decat (not an ACT piece)."

Apologies for that.

Well that is what I have too, and the first noise test put me at 106dB rather than 101dB. Very strange.

[Milky400]

A mate of mine has a monaro vxr with a electrically switchable silencer. Amazing piece of kit. I must say my tuscan is extremely quiet at 60-70 cruising not sure if it's been fettled with previously but suits me for long journeys and been commented on how quite it cruises.

As much as I love the noise at full pelt I must say its nice to be settled on a run

[firewallguy]

Byker28i said:

Did he have cats in?

I assume "linked decat" means not