Pretty sure it'll be to loud.
If you want to keep it quiet under normal driving conditions, but still have a nice note when you boot it, VCM Exhaust systems are great, and from what I hear, the KPM system is too.
Youll have to get one made up to suit your needs I imagine. Theres not much chance of any aftermarket exhaust, especially for a V8, being totally legal, but youd be able to get one made up by the above mentioned guys to be quiet in regular driving but loud when you open it up. SureFlo also do a pretty good one from what I hear.
If you just go the cat-back I cant imagine you will have any problems.
I have a Twin 3" xforce cat-back and its honestly not that loud, whether illegal or not im not sure, but my friends ricers are all WAY louder, even at idle.
There are two designs in 3 inch - medium and loud - medium should just scrape through - no chance with the loud system. Shop around though - not all workshops stock both kinds.