Thanks for your good words. But please note that this sound is made by V6 engine with same-length front pipe. This is the important point to make such a exhaust note.
This ex.pipe is made by one person who is supplying his arts for formula cars running for Formula-Nippon(like top categoly race in Japan.) And those arts are almost hand-made. The name is MEXC-S(you should pronounce this as MEX.). I know that he is producing the items for 156, 166, GTV. But one for 147 is now in development.
The following muffler is also worth to use. Unfortunately there is no samples of sound.
OVER(name of company) is also one of the options for whom don't want to use "commonplace one" for ALFAs.
I personally think that the exhaust pipes in Europe are too famous.
And sounds of those are just powerful, and don't make so high-pitched sound.
I am really pity that I can not introduce all of Japanese high quality ex/in pipes for all kinds of Alfa for you.
If you really want to know about the product line-up for 147 in Japan, I can inform you by PM or e-mail.
Only my concern about Japanese products is we have to pay much.
I don't like this.