Actually that's only part of the reason. The JoeZ exhaust (or any catback exhaust for the F) removes the secondary cats. The smog police don't like this. If you went for an inspection , and the inspector knew what he was doing on the visual, you would fail. The JoeZ tube would probably pass, if it was black and not the blue model. As far as noise, if you don't make a fool of yourself, you probably wont get stopped.
However, for me, the Borla or JoeZ are too loud, I have the stock mufflers with a true dual system that I had fabricated at a local exhaust shop, and yes, my secondary cats are gone. However, most folks like the extra noise. I only know of a couple of folks who have installed the JoeZ exhaust, and then removed it because of the increased noise.
2008 ISF - Mercury Metallic - Mine
2008 ES350 - Tungsten Pearl - Wife's
2011 Chevrolet Silverado - White - Ours