Hier der Auszug aus der Regulation 59 bezüglich der Kriterien einer Austauschabgasanlage, mir liegt die Regulation leider nur in Englisch vor:
6.2. Specifications regarding sound levels
6.2.1. Conditions of measurement
6.2.1.1. The sound test of the exhaust silencing system and the exhaust replacement silencing system have to be executed with the same
"normal" tyres, as defined in paragraph 2. of UN Regulation No. 117. The tests are not allowed to be done with "special use" tyres or "snow"
tyres as defined in paragraph 2. of UN Regulation No. 117. Such tyres could increase the sound level of the vehicle or would have a masking
effect on the sound reduction performance comparison. The tyres may be of used condition but shall satisfy legal requirements for in-traffic use.
6.2.2. The sound reduction performance of the exhaust replacement silencing system or components of said system shall be verified by means of
the methods described in paragraphs 6.2.1., 6.2.2. and 6.2.3. of UN Regulation No. 51. In particular, for the application of this point, reference
shall be made to the amendment level of UN Regulation No. 51 which was in force at the time of type approval of the new vehicle.
(a) Measurement with running vehicle
When the exhaust replacement silencing system or components thereof is mounted on the vehicle described in paragraph 3.3.3. above, the sound
levels obtained shall satisfy one of the following conditions:
(i) The value measured (rounded to the nearest integer) shall not exceed by more than 1 dB(A) the type approval value obtained under
UN Regulation No. 51 with the type of vehicle concerned.
(ii) The value measured (before any rounding to the nearest integer) shall not exceed by more than 1 dB(A) the sound value measured
(before any rounding to the nearest integer) on the vehicle referred to in paragraph 3.3.3. above, when this is fitted with an exhaust
silencing system corresponding to the type fitted to the vehicle when submitted for type approval under UN Regulation No. 51.
Where back-to-back comparison of the exhaust replacement system with the original system is chosen, for the application of paragraph
3.1.2.1.4.2. and/or paragraph 3.1.2.2.1.2. of Annex 3 of UN Regulation No. 51, it is allowed to have a gear change to higher accelerations and
the use of electronic or mechanical devices to prevent this downshift is not mandatory. If under these conditions the noise level of the test
vehicle becomes higher than the conformity of production (COP) values, the Technical Service will decide on the representativeness of the test
vehicle.
