Car Exhaust Noise

[The Black Flash]

Not seen this before, but good luck to the OP.
Ironically, when creating a new or highly modified vehicle that is subject to the IVA test (ie any kit car or something where you've modified the chassis, very basically), the limit is 98dB.

[Monkey boy 1]

According to Norfolk police IVA test is 99dB.

[GC8]

NFN

[PV7998]

We've all read the legislation, as have Norfolk Police, and the interpretation they are putting on it is that all they need is their opinion that it's a louder exhaust that the car came with as standard.
I'm assuming they've taken some legal advice in order to print this on their website.
Personally I wouldn't want to challenge a Police Officer's opinion in Court without some convincing evidence to the contrary.
The details about the testing method may not be relevant as they aren't trying to prove a specific noise level....they're just saying that in their opinion it's louder than standard. Is the level they tested above or below the limits in the legislation? because what isn't clear (to me at least) is that what is the position if the exhaust IS louder than standard but still UNDER the acceptable levels in the same legislation?

[Monkey boy 1]

That is the whole issue. An oppinion must be backed up with hard evidence and facts. If they did the test correctly the i wouldn't have a problem, but as they did it incorrectly to their own paperwork why shouls i roll over and submit.
I have had a solicitor look at the evidence and he said straight away that the test was done incorrectly according to the printed facts.

[PV7998]

I understand that the test may not have been done correctly, but from what I read they're saying that they don't need to do a test at all..........they seem to be saying that provided they can prove that the system has been "altered so as to increase the noise made by the escape of exhaust gases" then they have proved their case.
They say that they only need their opinion for this - as I said I assume they've had some legal advice about this.
It doesn't seem to matter whether there are any other features to the new or modified exhaust (more power etc) - all they need to prove is that it is more noisy.
BTW I am only speaking as Devil's Advocate in this....personally I hope it works out for you.

[NDA]

Had they tested it correctly, would it have passed their arbitrary test?

Leaving this area so open to personal interpretation by the Police, could lead to vindictive and spurious prosecutions.

[Timsta]

Surely they would also need to know the OEM db(A) to compare it to.

[NDA]

Timsta said:

Surely they would also need to know the OEM db(A) to compare it to.

Which will be as accurate as their mpg figures.

[Monkey boy 1]

Timsta said:

Surely they would also need to know the OEM db(A) to compare it to.

I have contacted Toyota UK, they do not have any records of the exhaust dB(A) on my modle of car, That didn't really surprise me as the car is 17 years old.

[herewego]

There would be no reason for them to have dBA figures for the car. It would be type approved after passing the drive by noise test procedure. The limit was set at 74 dBA in 1996 I think.

[rscott]

herewego said:

There would be no reason for them to have dBA figures for the car. It would be type approved after passing the drive by noise test procedure. The limit was set at 74 dBA in 1996 I think.

So presumably the police testing with a static (not drive by test) is completely irrelevant?

[herewego]

rscott said:

herewego said:

There would be no reason for them to have dBA figures for the car. It would be type approved after passing the drive by noise test procedure. The limit was set at 74 dBA in 1996 I think.

So presumably the police testing with a static (not drive by test) is completely irrelevant?

I'm not sure it's irrelevant but you could argue it's unnecessary since you only need an officer to testify that it makes more noise than a standard vehicle. It may be difficult to make this judgement for a vehicle that's only lightly noisier than standard but then those are not the ones that come to anyone's attention.
The police prefer to have numbers to refer to otherwise a prosecution can be expensive. If the static test is broadly equivalent to the drive by with sufficient margin for error then I guess magistrates will accept it. It appears that 82dBA static has been determined as equivalent to the 74 drive by and the police are adding a massive margin by using 90 since it's a log scale. I know there was a paper published on determining an acceptable static test, but don't ask me for it, I don't have it.

Edited by herewego on Tuesday 9th April 14:56

Edited by herewego on Tuesday 9th April 14:57

[rscott]

I seem to recall we've discussed this before. We interpret the regulations differently - I think you consider it to mean that the exhaust noise from the car cannot be any louder than when the car was produced.

I read it that it is not permissible to modify the existing exhaust system to make it louder, NOT that it is forbidden to replace the exhaust system with one which happens to be louder. if this were not the case, then it would mean that the various manufacturer approved exhaust upgrades available through franchised dealers would be in breach of these regs.

[DoubleSix]

I was wondering about that...

I mean, you can buy a BMW Performance exhaust from your dealer for that precise objective!

[Cotty]

I need a new exhaust on my BMW, the garage have said "I would reccomend only going for a standard stainless exhaust also, nothing sporty, as the exhaust note is part of the MOT test these days and anything louder than standard could be deemed as a fail if too excessive".

Do you think I should ask what the limit is on a 1992 E30 so I can make sure its under.

[Timsta]

Cotty said:

I need a new exhaust on my BMW, the garage have said "I would reccomend only going for a standard stainless exhaust also, nothing sporty, as the exhaust note is part of the MOT test these days and anything louder than standard could be deemed as a fail if too excessive".

Do you think I should ask what the limit is on a 1992 E30 so I can make sure its under.

This is exactly why I read "Using a vehicle with an exhaust system that has been modifies as to increase the noise made by the escape of exhaust gases" to mean drilling holes in the exhaust and associated idiotic actions.

[TinyCappo]

Cotty said:

I need a new exhaust on my BMW, the garage have said "I would reccomend only going for a standard stainless exhaust also, nothing sporty, as the exhaust note is part of the MOT test these days and anything louder than standard could be deemed as a fail if too excessive".

Do you think I should ask what the limit is on a 1992 E30 so I can make sure its under.

BMW engines are quite fussy about backpressure so if you can get a system as close to stock as possible I would.

[Monkey boy 1]

Timsta said:

This is exactly why I read "Using a vehicle with an exhaust system that has been modifies as to increase the noise made by the escape of exhaust gases" to mean drilling holes in the exhaust and associated idiotic actions.

Hmm, not thought of that angle of approach to the wording.

[Cotty]

I discussed this with the guy who tested my car. He agreed that it is a big grey area, he said a Suberu with a sporty sounding exhaust that came as standard could be louder than someone elses standard exhaust. He agreed that if I replaced my exhaust with one louder that would be ok as long as it wasn't excessive. Which considering I am not planning on fitting straight pipes and annoying the hell out of everyone seems a fair compromise.

Just need to find someone in Kent who supplies stainless steel exhausts for a BMW 325i E30 1992. I welcome any suggestions.