UN R51.03 paragraph 188.8.131.52, amend to read
Notwithstanding the requirements above, vehicles equipped with an ICE for propulsion are exempted from RD-ASEP, if:
- their exhaust silencing systems have no variable geometries and the vehicle has no sound enhancement systems, or;
- they are only equipped with sound enhancement systems fully in compliance with other UN Regulations.
Notwithstanding the requirements above, vehicles equipped with propulsion system other than ICE are exempted from RD-ASEP, if
- the vehicle does not have any sound enhancement system, or
- a sound enhancement system is fitted to the vehicle solely for the purpose of fulfilling the provisions of UN R138, and the sound emitting device(s) does not or do not as a sum emit a sound pressure level of more than 75 dB(A), when tested with the test procedure according to Annex 3, under the operation condition according to paragraph 184.108.40.206. of UN R138.