I’ve not seen the silenced system for sale but I read that as the standard ‘Tubi Sound’ and the louder sound is the ‘+Rumore’. There’s no ‘silenced sound’ on their site for sale so maybe they somehow quieten down the normal Sound exhaust ?
I think where people have 2 cars both with a Tubi Sound but think one is different from the other is possibly where 1 car has standard cats and the other has high flow sports cats. Most standard cats cut down the volume a great deal while high flow sports cats don’t. That’s certainly the case on a 348 anyway.