Sound of Impreza’s

Moin’s people, I have a short question to Impreza (wrx) – owner: I’m in North America and I’ve already seen some Subaru Impreza’s here, but above all I’ve heard. I think they were all wrx and respectively plus sti – versions, and what should I say, the sound is more than just horny. Extremely deep and (even if I love this one) at least as good as that of V8-Amis, which I hear very often… How does that come about? Are they serially like that? In Germany I never noticed that; drive there I have not yet had the opportunity to speak to one of the owners; what can you tell me about it? Do you know if there are land-specific differences? What is necessary to “create” such a sound? I am grateful for all the information! Merci, Greetings