We regularly get the question about what is the difference between the Euro3 and the Euro4 silencers.
Here the clarification.
The biggest difference between the two versions is the removable db-killer.
It is no longer removable on the Euro4.
From 1 January 2017, the new motorbikes are therefore subject to the Euro4 standard. This new standard therefore requires that the db-killer can no longer be removed without causing damage in order to be able to remove it. There are still a large number of models of motorcycles that are unchanged (as far as the exhaust is concerned) since the introduction of this standard, I just think of the MT-07, MT-09, BWM GS1200, etc …
For these bikes there are usually 2 versions available in the exhausts, Euro 3 and Euro4 (for models from 2017 onwards). Concretely, therefore, the Euro3 versions apply to this, they are only not legal.
For the new models after 2017 there will only be a Euro 4 silencer available. So keep in mind that your new silencer can have a welded db-killer. Some brands still make it quite easy to remove them, while others find it a lot harder or sometimes impossible to take them out. So, in case of doubt, ask a question!
Here is an explanation of how it is described in the new law.