Changes made by Commission Directive 81/334/EEC of 13 April 1981 adapting to technical progress Council Directive 70/157/EEC on the approximation of the laws of the Member States relating to the permissible sound level and the exhaust system of motor vehicles
EU Directive 1981/334
No changes made by Commission Directive 81/334/EEC of 13 April 1981 adapting to technical progress Council Directive 70/157/EEC on the approximation of the laws of the Member States relating to the permissible sound level and the exhaust system of motor vehicles are recorded.
From legislation.gov.uk's record of changes, the official one: see it there.