A video i made showing the EPA test procedure. After you receive a letter in the mail for excessive exhaust noise, you must take the vehicle to a licensed tester. The car is setup in such a way as the video shows. The car is revved up to 3/4 of it's operating range (4800rpm in this case) and sound pressure levels are recorded. As you can see, the standard exhaust reaches 82db on accel and 85db on decel. The current Victorian limits stipulate a 90db limit. The test costs $39.40 and is a simple pass/fail system. If you fail you will have to pay for another test.