2005 Idaho Code - 49-937 — MUFFLERS, PREVENTION OF NOISE

                                  TITLE  49
                                MOTOR VEHICLES
                                  CHAPTER 9
                              VEHICLE EQUIPMENT
    49-937.  MUFFLERS, PREVENTION OF NOISE. (1) Every motor vehicle shall at
all times be equipped with a muffler in good working order and in constant
operation to prevent excessive or unusual noise and annoying smoke, and no
person shall use a muffler cut-out, bypass, or similar device upon a motor
vehicle on a highway. When any motor vehicle was originally equipped with a
noise suppressing system or when any motor vehicle is required by law or
regulation of this state or the federal government to have a noise suppressing
system, that system shall be maintained in good working order. No person shall
disconnect any part of that system except temporarily in order to make
repairs, replacements or adjustments, and no person shall modify or alter that
system or its operation in any manner, except to conform to the manufacturer's
specifications. No person shall knowingly operate and no owner shall knowingly
cause or permit to be operated any motor vehicle originally equipped or
required by any law or regulation of the state or the federal government to be
equipped with a noise suppressing system while any part of that system is
disconnected or while that system or its operation is modified or altered in
any manner, except to conform to the manufacturer's specifications.
    (2)  The engine and power mechanism of every motor vehicle shall be so
equipped and adjusted as to prevent the escape of excessive fumes or smoke.
    (3)  No person shall modify the exhaust system of a motor vehicle or a
motorcycle in a manner which will amplify or increase the noise of the vehicle
or motorcycle above that emitted by the muffler originally installed on the
vehicle by the manufacturer.
    (4)  A showing that the sound made by a passenger motor vehicle or
motorcycle exceeds the maximum allowable decibel level shall be prima facie
evidence of a violation of subsection (1) of this section.
    (5)  No person shall sell, offer for sale, or install any noise
suppressing system or device which will produce excessive or unusual noise.