With phone lines and DSL the important things are to keep the twisted pairs as intact as possible, and not to have any stubs before you have the DSL filter. After the filter you have POTS and it does not worry the DSL signal at all, you can have almost anything there with minimal effect, but before you want to have the twisted pair, good connections and no large open loops, and the cheap flat cable to the DSL modem and the filter must be as short as possible, and use good connections.
As you are getting very close to the peak for the service you have, the line is good signal wise, and any improvements will be done by cleaning all the connections from the actual cable to the DSL modem up to the point you meet the actual phone company line side, after which you are stuck with having Telephonica Italia come out and check the line with a TDR analyser, and finding which of their joints is causing a reflection and fixing that side.