Georgia code
"(c) It shall be unlawful for any person to sell or offer for sale any muffler which causes excessive or unusual noise or annoying smoke or any muffler cutout, bypass, or similar device for use on a motor vehicle or for any person to use, to sell, or to offer for sale any motor vehicle equipped with any such muffler, muffler cutout, bypass, or similar device. Any person violating this subsection shall be guilty of a misdemeanor."
It's illegal to have operate a vehicle in Georgia, and probably all of the other 49 states, with a loud exhaust. Cops can, and do write tickets for this. I have gotten a ticket for this in NJ. I was 18 and the ticket convinced me to put the stock exhaust back on my 240Z because it was a lot easier to drive around without having to worry about getting stopped all the time.
Fight the power as much or as little as you want. It can get pretty expensive doing obvious illegal mods to your vehicle.
It's like those stupid blue lights people put all over their cars and ride around with. Have at it. The fines they pay keep my taxes down.