Dirtyswiff

My guess is because as a producer/ manufacturer company they intend on selling nationwide and in some cases other countries however, exhaust sound restrictions vary from place to place . Very necessary for us, but most Likely not so important for them to release unnecessary information to a crowd where probably only 25% have sound restriction laws on exhausts in their state .

catchb52

Not to get off the subject, but isn't it interesting that we see all these hot rod shows where they are putting all manor of powerful engines in older cars, but the police get allover you if you change anything on a newer car.

alnielsen

iTrader: (4)

There are free smartphone apps that read sound db. I don't think they are accurate (I installed one), but it should be close enough to be a guideline.

alnielsen

iTrader: (4)

Have you ever seen the disclamer For Off Road Use Only. That way they don't have to test it and make certain that it is legal for all jurisdictions. Also, how can they certify an aftermarket part when the customer will likely mix it with other aftermarket parts.

All SCCA events have sound requirements. Most other sanctioning bodies do the same. Some tracks have lower requirements do to local laws. One of our local tracks used to do things for this farmer neighbors (like give away firewood) so they would be less likely to complain about noise. This was back before 1985 when general noise requirements became mandatory. Ironically, it was probably the open exhaust rotaries that started the movement. They were ear piercing.

Karack

i figured the argument about altering the engine would affect the noise levels would come up, which is why i'd just do a single test on an otherwise stock car just for a baseline.

Dirtyswiff

Your a genius AL! how could I have not thought of that myself? I'm still gonna going to reinstall my oem equipment for the test. But it's good know I can purchase something that will cost less then $1 just to get an idea of the sound range of the many different pipes and catbacks I have and will put together. I just read a review on this app called decibel reader pro, some guy said his town was having a rooftop nightclub problem and he reported it to the local authorities where they in turn used the app because it's so accurate to turn down they're efforts to have the nightclub shutdown. That sold me.

alnielsen

iTrader: (4)

I have a free one called Sound Meter Lite by Smart Tools (android). A lot of people seem to like it from the reviews on G Play.

Dirtyswiff

I think people on this forum have more androids then iPhones. I have a iphone 5. I'm sure I can get free one but it probably lacks certain features of course. Like computer access and data.

ken-x8

On the iPhone, try Decibel 10th. It's free. It records the data. If you tap on the data plot at the top, you can e-mail the numbers, then do whatever you want with them on your computer.

Just turn off the sound effects feature, lest it records itself.

Ken

Karack

the app would probably have to be designed for a particular phone and its mic, otherwise the accuracy of the input goes to hell.

ken-x8

I'd be amazed if an iPhone microphone was anywhere near adequate for serious noise measurements. You can get Type 2, maybe even Type 1, microphones that will plug into smart phones and pads. You can also buy better apps, even spectrum analyzer apps.

But the one I mentioned seems to be generally in the ballpark, has a certain charm, and is free. One of these days I need to try it against a real sound level meter.

Ken

Dirtyswiff

I seen that app too. Thanks for the heads up. I'll use it this Sunday when I do the swap. I'll measure the sounds of the oem cat with the oem catback, also the oem cat with the ap catback. And I will compare with the results for the oem setup when I get it tested next week. Well get to the bottom of this.

OtherSyde

Oh I don't have it installed, but I do have the lightly-used OEM cat in my hall closet, ready to swap out with the mid-pipe at a moment's notice. With the stock air-box already re-installed, do you think re-installing the OEM cat would allow me to pass a smog test with the GReddy cat back installed as well? Or would I need to replace the cat back with a stock exhaust just to get the car registered in Cali..?

Dirtyswiff

Ur catback has nothing to do with emissions bro, The only problem you'll have about your catback is the sound it resonates. That's the issue I'm having I know forsure I can pass with my agency power catback because I have. But since I'm going to the state referee and not just a normal smog station, if I decide to keep my aftermarket catback on when they do the visual and the decibel reading I will fail.

OtherSyde

Damn, that is seriously ghey. So I should probably just have a stock exhaust in reserve for when theyinevitably get me anyway, huh? I've heard it said that a lot of the cops hate imports in Cali, and will often target them more-so than 'Murican cars like Camaros and Mustangs...

Alfcam

I have been through this before. I'm in California and the state ref I went to was on the Yuba College campus in Linda, CA. They went under my car to check the exhaust and they put a machine at your exhaust tip and rev to a certain rpm and take the reading at whatever rpm some guide they have tells them too. Put the whole exhaust back to stock because if not they ask for CARB numbers for it.

Dirtyswiff

Thank you, this is very credible advice.

ShellDude

iTrader: (12)

https://play.google.com/store/apps/d...=kr.sira.sound

OtherSyde

I've got the stock air box and stock cat, but I've been searching all over the internet, and apparently there is no such thing as a CARB number for the "cat-back" section of the exhaust - not even for the stock exhaust. So I'd be kinda crewed either way, stock or aftermarket, right?

What about a MazdaSpeed cat back exhaust, is there one for the RX8? Like, it has the Mazda name brand on it, so it would look stock and pass a visual inspection?

alnielsen

iTrader: (4)

That's the one I was talking about earlier.

catchb52

It all depends on what your state laws say. First issue is having an exhaust system that has been approved by CA. Probably going to have to check the large aftermarket exhausted manufactures. They are probably the only ones that are going to put in the time, effort and money to get this certification.

As for measuring decibels, I do industrial hygiene for a living. The phone apps are not that bad. They will give you a good idea where you are on noise. I use one for quick spot checks to see if I need to monitor with more sensitive equipment.

There are also a number of ways to measure exhaust noise. I am not sure which one CA uses. Here is a link to one that some states use. Note. Those is a 2006 document and there may be a newer one. http://www.ntc.gov.au/filemedia/Repo...stSept2006.pdf

Dirtyswiff

Thanks for your input, I wonder if I just call or email agency power, and see if they will give me legal advice about my situation. Or maybe a carb number for the catback or something.

Dirtyswiff

How true is this btw? Carb numbers For the catback?

ken-x8

That sounds like the best thing to do. Since they made it, they can tell you if it's California legal and give you any supporting info.

Ken

Karack

the catback does NOT need to be CARB certified, it does not affect emissions whatsoever. it does change exhaust noise levels though.

CARB stands for California Air Resources Board, ie it is a bureau dedicated to smog emissions and not sound laws. so technically there is no catback made that has any CARB certification.

if the ref is hassling you about a catback for a CARB certificate i would start to question the credibility of that station, their testing standards and take the car to another referee or call their supervisors. the catback only needs to meet the sound requirements and does not need any other certification.


you know it's getting retarded in the state when you have to argue about the emissions of parts that have no effect on emissions. what's next, testing vapors emitted from the interior plastics of the car? tell them to test the noise emissions and stop FFing about carb labels after the cat.