§ 205.165 Definitions.

(a) As used in this subpart, all terms not defined herein have the meaning given them in subpart D of this part or in the Act.

(1) Category means a group of exhaust systems which are identical in all material aspects with respect to the parameters listed in § 205.168 of this subpart.

(2) Exhaust header pipe means any tube of constant diameter which conducts exhaust gas from an engine exhaust port to other exhaust system components which provide noise attenuation. Tubes with cross connections or internal baffling are not considered to be “exhaust header pipes.”