I had an Eventuri kit on my car when they came out a few years ago. It did give a nice induction noise alright. It wasn't very loud, but it was loud enough that when I removed it I really noticed the exhaust note again.
I didn't really give any performance gains, none that I could feel anyway.
I sold it after a year as I felt the money could be put to better use. I bought mine second hand though and got all my money back on it so that's a good option if you just want to try it out.