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Requirements for Exhaust Noise Certification

The Low Volume Vehicle Technical Association (LVVTA) plays a crucial role in ensuring that scratch-built or modified vehicles meet the highest safety standards. If you are considering building or changing a light motor vehicle in New Zealand, it is essential to understand the technical requirements for exhaust noise certification. Let's dive into the criteria outlined in the LVVTA.

The primary purpose of the exhaust noise certification standard is to establish a set of technical requirements and a testing process for measuring exhaust noise emissions. This standard is crucial for ensuring that vehicles comply with international best practices and meet legal requirements. The standard aims to provide accurate, repeatable, and legally defensible outcomes by conducting objective exhaust noise emission tests.

Section 1: Scope and Application of this Standard

1.1 Scope of this Standard

1.1(1) This low-volume vehicle standard applies to all light vehicles, excluding specific categories, subject to objective exhaust noise emission tests. This includes production vehicles undergoing entry or in-service compliance and scratch-built low-volume vehicles registered in New Zealand.

1.1(2) Exceptions to this standard include powered bicycles of Class AB, vehicles not powered by internal combustion engines, production vehicles with unmodified original equipment exhaust systems, and vehicles referred for exhaust noise emission testing solely due to exhaust leaks or poor exhaust system conditions.

1.2 Application of this Standard

1.2(1) Light vehicles requiring exhaust noise certification must adhere to all technical and procedural requirements outlined in the standard. While such vehicles may not technically be classified as low-volume vehicles, they are referred to as such for clarity within the standard.

Regarding exhaust noise certification, compliance with these requirements is essential to ensure that vehicles meet legal standards and not emit excessive noise levels. Failure to meet these criteria can result in penalties and possible enforcement actions.

Why is Exhaust Noise Certification Important?

Ensuring that vehicles comply with exhaust noise certification requirements is vital for several reasons:

  • Legal Compliance: Meeting exhaust noise standards is a legal requirement in many jurisdictions to ensure public safety and environmental protection.

  • Noise Pollution Control: Excessive noise emissions can contribute to pollution, adversely affecting public health and well-being.

  • Vehicle Performance: Proper exhaust noise control can also enhance vehicle performance and efficiency, improving the driving experience.

Twin Exit Exhaust Toyota GT86

Technical and Procedural Requirements

Exhaust System Requirements

Regarding exhaust system requirements, LVVTA Standards 90-20(05) outline several key criteria that must be met. Firstly, the exhaust system fitted to a low-volume vehicle must have a good design using suitable materials. It must also be in good condition and free of leaks, securely attached to the vehicle using a mounting system that allows for necessary engine movement without stressing the exhaust system.

The body of the vehicle must be sealed in areas adjacent to the exhaust system to prevent the entry of any exhaust gases into the passenger compartment. The exhaust system must also be designed, constructed, and fitted to prevent removal, alteration, or interference without hand tools.

Exhaust System Design and Condition

The design and condition of the exhaust system play a critical role in ensuring compliance with exhaust noise certification standards. The system must be positioned so that it is isolated from the passenger compartment and terminates where the outer end of the exhaust pipe is not directly underneath the passenger compartment.

In addition, sections of the exhaust system that extend beyond the outer longitudinal extremity of the vehicle must not present any open exhaust tubing or sharp edges facing toward the front of the vehicle. Any exposed exhaust adjacent to occupant entry and exit points must be adequately heat-shielded to prevent burn injuries.

The exhaust system must be constructed to prevent interference and alteration of its performance or operation, ensuring that the specified decibel levels are not exceeded. This is particularly important when considering using multi-mode exhaust systems in scratch-built or modified vehicles.

Test Site Requirements

A suitable test site must be utilised to conduct exhaust noise emission testing. The test site should be predominantly flat within the immediate test area, with a space free from large sound-reflecting surfaces such as buildings, walls, vehicles, trees, or shrubs within a radius of at least 3 meters from the sound level meter microphone.

Testing may be carried out under a canopy as long as no part of the canopy is within 3 meters of the sound level meter microphone. The use of a location with a solid ground surface and minimal sound-reflecting surfaces is essential to obtain accurate and repeatable test results.

Decibel Level Requirements

In the realm of exhaust noise certification, decibels play a significant role in determining whether a vehicle meets the standards set by regulatory bodies. The maximum permissible decibel level emitted by a low-volume car must not exceed certain limits. For example, a moped must emit no more than 91 dBA, while motorcycles with engine capacities ranging from 125 cc to over 125 cc have varying decibel limits.

Decibel Limits

According to the LVVTA Low Volume Vehicle Standard, different classes of vehicles have specific decibel limits that must be adhered to. For vehicles manufactured before January 1, 1985, the decibel limit is set at 95 dBA. However, for vehicles manufactured after this date, the limit varies depending on the registration date in New Zealand. For instance, vehicles registered before June 1, 2008, must emit no more than 95 dBA, while those registered on or after this date must stay within 90 dBA.

Decibel Factoring for Specific Situations

Factors may be subtracted from the average decibel level recorded during testing to account for specific circumstances affecting the emission figures. For example, a factor of 4 dBA may be subtracted if the engine is positioned to the rear of the driver or the exhaust outlet is within 1.5 meters of the engine. Similarly, a factor of 2 dBA may be subtracted for vehicles with certain engines or components emitting high levels of mechanical sound.


Understanding the requirements for exhaust noise certification is essential for ensuring your vehicle complies with regulations. By knowing the decibel level requirements, limits, and factors that may affect emission testing, you can take the necessary steps to obtain certification without any issues. Remember, staying within the specified decibel limits is key to meeting regulatory standards and ensuring a quieter driving experience for all.

To meet the requirements for exhaust noise certification, vehicle owners must ensure that their cars emit sound within the specified decibel limits, as mandated by the LVVTA Low Volume Vehicle Standard. By keeping track of the decibel level requirements for different classes of vehicles and factoring in specific situations that may affect emission testing results, you can successfully obtain certification and enjoy a quieter driving experience on the road.


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