The following words and terms, when used in this chapter, have the following meanings, unless the context clearly indicates otherwise:

Efficient—A muffler shall be considered efficient if it complies with the following conditions:

1. (i) The muffler has the effect of substantially reducing the noise from the motor over that which would be created if the muffler were removed, bypassed or otherwise rendered inoperable.
2. (ii) In comparison to motors of similar characteristics, under similar operating conditions, the noise created by the motor with the muffler in question is not substantially greater.

3. (iii) The muffler prevents excessive or unusual noise as defined in § 119.5 (relating to stationary test).

   Muffler—A sound suppression device or system designed and installed to abate the sound of exhaust gases emitted from an internal combustion motor and which prevents excessive or unusual noise.