The United States has a 50-state patchwork of exhaust noise laws, with every state having its own metric for determining whether a car is too loud. Many states have subjective laws that say a car is too loud if it makes "excessive noise" without defining what that means. When states enact overly vague or poorly worded laws pertaining to vehicle noise, it can have a chilling impact on the ability of SEMA members that produce aftermarket exhaust products to sell and install their products. On the other hand, California has implemented SEMA's model legislation, which sets a limit of 95 decibels using an objective testing method to determine if a car is too loud. SEMA supports this model and advocates that other states adopt similar laws regarding noise ordinances.
Noise cameras are an emerging technology that's increasingly used to determine whether a vehicle is in compliance. SEMA has raised concerns about this technology and does not support its premature implementation for two reasons. First, like a red light camera, these noise cameras take photos when a vehicle is above the specified decibel level. However, if multiple cars are simultaneously on the road, there is no definitive way to determine which car is in violation. This can result in unfair ticketing of drivers. Secondly, when implemented in urban areas, tall buildings can reflect and amplify the sound, making it even more challenging to determine if a vehicle is in violation.
SEMA supports further research into this technology and believes that it should only be introduced once all the concerns associated with the pilot are addressed.