(32)Experience has shown that it is appropriate to allow a wider range of conformity assessment modules for components. As regards conformity assessment of exhaust emission and noise emission requirements, a distinction should be made between the cases where the harmonised standards have been used and where they have not, since in the latter cases, it is justified to require a more stringent conformity assessment procedure. Furthermore, the possibility of using the reference boat data for noise emissions testing should be suppressed as superfluous, since it has not been used in practice.