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[Jerry/MD]

I see many posts asking about sound levels on exhaust systems. Everybody has a different opinion on what is loud...or not loud enough. Why can't the manufacturers come up with a standard measurement...list the parameters (engine size, etc) and provide the numbers for comaprison? Being an engineer I like to compare numbers. This subjective stuff drives me nuts.

What do you think?

[Twolanerider]

Any standardized baseline would be nice.  Though many would have trouble applying the standard.  The engine pushing the pipes makes a surprising amount of practical difference.  Out in my garage right now D&D FatCats with quiet baffle are on a stock 88, a 95 with just a tiny compression bump and a cam change and a 107 with even bigger cams and more compression.  Distinctly different sounds from each exhaust. 

[Steve Cole]

There are standards already. Most aftermarket suppliers do not want to test them as the government would then have them by the short hairs. There are federal laws in place for the max noise level allowed for any public use. So if a manufacture knowingly sold a system that was too loud by following the test standards they would be in it deep.

[pm203]

That is why these same manufacturers have disclaimers on their sites advising you that their exhaust systems are off-road use.

[VaEagle]

I would guess there would be too many variables that could affect testing. Things like what sound meter is used and was it calibrated the same as another company's. Was it at the same distance and angle from the exhaust, was the air temp and humidity the same, was it at the same altitude.
As stated already then you throw in motor changes like different cams etc. not just by the owner but what if the manufacturer makes internal changes from one model year to the next?
I think sound is a very subjective thing and what may be music to someone could be noise to you or vice versa based on things like tone not just a specific volume.

[Jerry/MD]

I would guess there would be too many variables that could affect testing. Things like what sound meter is used and was it calibrated the same as another company's. Was it at the same distance and angle from the exhaust, was the air temp and humidity the same, was it at the same altitude.
As stated already then you throw in motor changes like different cams etc. not just by the owner but what if the manufacturer makes internal changes from one model year to the next?
I think sound is a very subjective thing and what may be music to someone could be noise to you or vice versa based on things like tone not just a specific volume.

All the things you state would be the 'standards' that all manufacturers use. Meter distance, height, environment, stock engine, etc. I'm not concerned about the absolute sound level...I'm looking at comparing each type.

[Midnight Rider]

There are standards already. Most aftermarket suppliers do not want to test them as the government would then have them by the short hairs. There are federal laws in place for the max noise level allowed for any public use. So if a manufacture knowingly sold a system that was too loud by following the test standards they would be in it deep.

That's it precisely...Although it would be nice information to know.

[willyB]

Maybe a better way to define the sound levels of a muffler would be to offer an "Air Flow/Volume Rating" (a rating that combines air flow and static pressure) to each muffler and set a number to that.

For example:
** A stock muffler with would be assigned a rating of 1. (Restricted air flow and high static pressure)
** A V & H High Output muffler with a significantly less restrictive flow would be assigned a rating of 5.

Seems pretty simple to understand and the manufacturers are not shouting decible numbers.

[Dead_Reckoning]

There already is a standard with the newest revision of Maine's "Loud Noise" Law
Must adhere to
Society of Automotive Engineers - J2825
http://www.cyclepedia.com/sae-j2825-standard/

This is beginning to show up on some aftermarket exhausts.
SuperTrapp Stout 4” Slip-Ons -
At 95.6 dB @ 2,000 rpm, or 2.4dB over stock. SuperTrapp Stouts are SAE-J2825 sound compliant.
http://www.supertrapp.com/product_sections/cat.asp?CatID=85

I noticed a few more as well. Memory escapes me at the moment.

SAE J2825 Sound Test
http://www.ultimatemotorcycling.com/SAE_J2825_Motorcycle_Sound_Test

A retire LEO told me that All Lawas are "Vouluntary Compliance". If you do not mind paying the fine, the law doesn't stop you.
Also,it depends on wether or not Law Enforcement choses to enforce the law. Many also ride Bikes.

What happened here in ME was that legit complaints went unanswered until a group was able to pass a Noise Law.
Until Riders and Residents can work together and both use discretion, I see the laws only getting stricter.


DR

I see many posts asking about sound levels on exhaust systems. Everybody has a different opinion on what is loud...or not loud enough. Why can't the manufacturers come up with a standard measurement...list the parameters (engine size, etc) and provide the numbers for comaprison? Being an engineer I like to compare numbers. This subjective stuff drives me nuts.

What do you think?

[Steve Cole]

The federal laws currently on the books apply to both on and offroad applications for noise standards. So if they tested by the standard rules and failed they could not knowingly sell them. While enforcement is a whole nother bag of worms, let's just say that the exhaust guys are playing in the grey area of the laws. Sometimes it's much better to not know than to know the answer and fail to follow the law afterwards.

[JCZ]

I would guess there would be too many variables that could affect testing. Things like what sound meter is used and was it calibrated the same as another company's. Was it at the same distance and angle from the exhaust, was the air temp and humidity the same, was it at the same altitude.
As stated already then you throw in motor changes like different cams etc. not just by the owner but what if the manufacturer makes internal changes from one model year to the next?
I think sound is a very subjective thing and what may be music to someone could be noise to you or vice versa based on things like tone not just a specific volume.

[/b]

Hit the nail on the head.    There was a time when deep tone and loud (= Thunderheader) were my priorities.  I've crossed over to the dark side.....now the priority is "best performing exhaust and quiet as possible".    (=  Fullsac 1.75 baffles in stock exhaust)