Neb. Rev. Stat. § 60-6,371: Exhaust or intake muffler; change; increase of noise; prohibited.

No person shall modify or change the exhaust muffler, the intake muffler, or any other noise-abatement device of a motor vehicle in a manner such that the noise emitted by the motor vehicle is increased above that emitted by the vehicle as originally manufactured. Procedures used to establish compliance with this section shall be those used to establish compliance of a new motor vehicle with the requirements of sections 60-6,363 to 60-6,374.