I've got Yozza with silenced NW Performance decat.
Tbh with cat in the Yozza it is similar volume to standard at motorway. Only alot louder than standard underload from 3-4k and on idle, normal driving it's similar to standard and very managable. Don't let ppl tell you they're too loud.
I got a silenced decat for it as I've seen and heard a Yozza with a unsilenced decat and it is VERY loud. However with this silenced decat in it's very good. It's a little louder now at all times but not much so. Underload and caning it you can really tell the difference and it sounds f**king amazing. Before, for an aftermarket exhaust, I thought it was a little too quiet when at the top of the rev range, well for me anyway. But I'm used to a Magnex with decat on a Williams which was like the end of the world.
What you and others need to know is the acid test: my wife like most women has no interest in cars and likes to go around with little noise and hassle. She is not put off by this exhaust at all. It really is very good.