Harley Davidson for beginners and beginners

Hello I have discovered my passion for the Harley again after almost 5 years, actually it was never completely gone but the last years I was just someone who looked at the spectacle from the “Tellerrand”. But now I have to do really seriously before my motorcycle show next year and then it is to become a Harley Davidson Nightster. I already deal with some questions in advance that many of you are already an old hat. Despite in-depth search in the Int ernet I could hardly find satisfactory answers to my questions, so I once allowed myself to open up such a beginner area here, because there is certainly more like me. As I said the questions I have, would be occupied only when I really have the bike standing there but I would like to know a lot already. So first of all a question that many of you certainly have never dealt with before. ^^ What about the helmet regulation? I would like to have a Big German (Wehr The helmets that I have seen have no CEC approval, but are sold under motorcycle requirements. Are such helmets allowed without restrictions in Germany or are you in danger of being stopped because they are not allowed? How does the sound technology with the Nightster look like? I would like to put on the helmet) I was told that it doesn’t matter in Germany, however, seems rather unbelievable to me, in a country governed by regulations like ours. If you like to have a Harley-typical sound, but without this typical German whispering crayon, are there legal ways to make it possible?