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I borrowed my bosses dB meter today and took some measurements for me car. Inside at idle was 78~79dB, inside under a light cruise was 87~89dB. Outside at the tip was 108~109dB and about 5 feet away was 82~83dB. Thas it, fascinating eh? Just thought I'd share.
 

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So where are you supposed to measure it from to check to see if it meets the noise requirements to be legal?
 

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Dunno, I can't seem to find anything about a distance. But it looks like 95dB is the legal limit in California. Hopefully thats 95dB from 5 feet away...
 

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What kind of exhaust?

I think its 5ft away... for some reason that sounds right, but don't hold me to it
 

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I tought it was more like 10ft away in a 50 by 50 foot room.

I'll see what I can find.

Tats.
 

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Sorry to burst your bubble, but it's from a distance of 20" in the direction of the tip's angle. The 10' rule is regarding objects in the vicinity. Besides the ground, meter and car, no object should be within a 10' radius of the meter.

There's also a difference between dbA and dbC. You might wanna check the meter to see if it has those two weighting options. The A and C is for the weighting. If I'm not mistaken, A is for levels the ear can hear, and C includes levels we can't hear. The limit in the Nazi state is 95 dbA.

I've been known to be wrong, however, I feel I'm quite accurate when it comes to these matters.
 

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Discussion Starter #9
ivbdn said:
Sorry to burst your bubble, but it's from a distance of 20" in the direction of the tip's angle. The 10' rule is regarding objects in the vicinity. Besides the ground, meter and car, no object should be within a 10' radius of the meter.

There's also a difference between dbA and dbC. You might wanna check the meter to see if it has those two weighting options. The A and C is for the weighting. If I'm not mistaken, A is for levels the ear can hear, and C includes levels we can't hear. The limit in the Nazi state is 95 dbA.

I've been known to be wrong, however, I feel I'm quite accurate when it comes to these matters.
I'll have to re-check from 20" at 3K. I'll also make sure its displaying dbA. Sounds like you've had some experience dealing with this law?

Kotir: Borla headers, Stromung midpipe, ScoobySport muffler.
 

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Yeah..I've had the experience twice already. I never fought it in court cuz if it came down to proving I was 95 dbA or lower, I wouldn't pass. I was at 120 dba at 3k rpm. Since then, I've had a glasspack resonator put in which helped out. Putting in the headers shut it up even more surprisingly.
 

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ivbdn said:
Yeah..I've had the experience twice already. I never fought it in court cuz if it came down to proving I was 95 dbA or lower, I wouldn't pass. I was at 120 dba at 3k rpm. Since then, I've had a glasspack resonator put in which helped out. Putting in the headers shut it up even more surprisingly.
Holy crap, 120dba? What kind of exahust were you running? I generally don't agree with such laws, but there is a point where a car is too loud. Of course it shouldn't matter if you don't tear through neighbhorhoods and such.

JC
 

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20 inches? Highly unlikely. I suspect it is more like 6 to 9 feet, if not more.

Trivia: SPL drops by 50% every three feet from the source of the sound. So, if something is 100 Db at 3 feet, it should be 90 Db at 6 feet, 80 Db at 9 feet, etc.
 

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I've got a Hayame XT1 universal muffler w/ custom piping (2.25"). It wasn't annoying loud. Just really rumbly and bassy loud. The vibes used to lightly rattle the windows and shake the house.

Just starting it would set off alarms of cars that were right next to me (only if they were really sensitive). Coasting through garage parking lot(I've got a 4EAT) w/o even giving it gas was good enough to set off the warnings of car alarrms.

It was loud, but like I said, it wasn't annoying loud, but very intimidating. I'd get revved on a lot, but a quick rev back made them think twice. And when it would shift at WOT, it sounded like there was some sort of explosion making it sound not like a 4EAT, but not a manual either. It's too bad that I had to put a resonator on it :( .

In regards to the 20" thing...I'm 99% sure it's 20" from the tip. I used to have a copy of the procedure on how to take it, but if you prove me wrong....then I stand corrected.
 

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Discussion Starter #14
Re-checked, and 20" from the tip I'm 117 at 3,000 RPMs. Ah well. Oh and it is a dbA meter.
 

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Does your mid-pipe have a resonator? If you're worried about noise level, slap one on and you should be ok. I have a glasspack (I'm still @ ~ 105). A stainless of course would be better.
 

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Discussion Starter #16
Nah, I'm not really worried, I just thought I'd share the results. I haven't really had any run-ins with any Nazi-cops.
 
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