I don't agree, it is the test that is standard and yes, it is important to have a decent sound level meter, but mine is a type II with current calibration and I have spot checked even a cheap Radio Shack meter and when new, they are fairly accurate.
The point is to take what ever exhaust system you have, get sound level data using the steps outlined in the standard and then you can describe the exhaust system you have, the meter used, the dB results and then anyone using "exactly" the same components should get about the same results. If they want to modify the exhaust but want a quieter system, it would provide a way to compare -not perfect, but more meaningful than recording and posting how it sounds.

 

only that if we pick a standard that defines the test conditions and we all do it the same way, then we can keep a list of Pipes, Mods etc., to see how affect the dB

Agreed. I did SAE J1287 from memory and in an informal way.
Or I thought I did anyway.

The dimensions an angles were approximations.
I was inline and had the meter at ~45. That was wrong.
For my own benifit I'll retest at 45 and report back.

BUT,
It is kinda comparitive only as it has been stated several times that underload you throw the SAE J1287 results out the window.

Those who are talking about "comparison" are on the right page.
SlapDrum

 

That whole "Who Cares?" thing.
If you think you are loud and live in Cali. You only start to care when you are confronted my a Ranger (cop etc) that has the ability to cost you money