The muffler on your car has a vital job to do. Mufflers feature a series of perforated tubes or chambers that control the sound coming from the exhaust system. If the muffler doesn't work properly (or you modify the system to work in a different way), your car may create enough noise to fall foul of New South Wales laws. Learn why people modify mufflers, and find out how these modified systems could get you into trouble with the police.
Why people modify mufflers
A new, efficient muffler is a surprisingly complex device that relies on precise calibration. A muffler's design allows sound waves to come into the system and then bounce around in such a way that one frequency cancels out the other. In this way, mufflers can drastically cut down the noise a car's exhaust system makes, which is good news for anybody who lives in a quiet residential area.
Of course, when it gets to this kind of precision engineering, experts can also modify the way a muffler works to create certain effects. For example, you can 'tune' the way a muffler works, so your car creates a certain type of sound. Performance car enthusiasts particularly like this kind of tuning.
Mufflers don't generally boost a car's performance. By design, these systems create resistance in the exhaust system, which stops air getting through the pipe as quickly as possible. As such, some people also modify their muffler so it doesn't interfere with the car's performance. By doing this, you will normally hamper the muffler's ability to control noise, which, in turn, could mean your car breaches New South Wales noise laws.
Road traffic noise
A lot of people think that road traffic noise is a significant problem. In fact, a survey in 2004 found that around 46 percent of people living in New South Wales see this as an issue. What's more, a 2003 study found that around 20 percent of people living in Sydney have to put up with road noise that's above the safe guidelines issued by the World Health Organization.
There are several noise control regulations in New South Wales. For example, rule 224 means you cannot use your horn unless it is to warn another driver about a potential hazards. Road rule 291 means that it's illegal to start or drive a vehicle in a way that makes unnecessary noise. Revving the engine too hard would fall foul of this law.
Laws also affect the permitted noise level from your car's exhaust system.
Exhaust noise levels
The noise your exhaust can legally produce depends on the age of the car and whether the vehicle is certified to Australian Design Rule 83/00, which came into effect from 2005.
For cars built before 1983 and certified prior to ADR 83/00, the legal noise limit is 96 decibels.
For cars built after 1983 and certified prior to ADR 83/00, the legal noise limit is 90 decibels.
For cars built before 1 September 2011 and certified to ADR 83/00, the legal noise limit is the higher of the pre-ADR 83/00 limit or the ADR 83/300 signature level plus 5 decibels.
For cars built after 1 September 2011 and certified to ADR 83/00, the legal noise limit is the ADR/300 signature level plus 5 decibels.
As you can see, the rules are relatively complex to interpret, but you can face a fine if you break them. An environmental officer can issue a penalty notice with a fine of between $150 and $1,000.
What's more, either an environmental officer or a traffic cop can issue you with a penalty notice for driving a vehicle when the noise control equipment (the muffler) does not work properly. This definition can apply to a defective muffler, a muffler that you haven't fixed in place securely or a muffler you have modified. Selling a vehicle in this condition is also an offence.
In all cases, an officer can also issue you with a defect notice. This notice means that (as well as paying the fine) you must put right the problem. If you don't, the Environmental Protection Authority can suspend your registration.
Car owners in New South Wales must make sure their car's muffler is not faulty or modified to exceed legal noise limits. For more advice, talk to a trained mechanic or mufflers specialist.