Had a Cybox on our 20V N/A for about 10 years, yes it is noisier than stock, but no way is it horrendous, inside the car is okay, not much difference really from stock. Off the revs it is pretty quiet, give it the beans, then yes it gets louder, would I change it, Hell will freeze over first.
Not sure why Cybox have withdrawn the recommendation, it does not warrant the "Track Day" comment nor annoying the neighbours, I've never had a complaint.
Now my Harley, that makes a noise har har.
John