It's all about what you do with it.
If it sounds like a ricer, you'll get tagged with a fine.
If it sounds good, AND not insane, AND you're not revving the engine or being otherwise obnoxious with it - no problem.
I have loud pipes on my motorcycle. Loud enough that after a couple hours with a helmet my ears are ringing a BIT - riding in a parking garage it sounds like a AAA Dragster launch when I drop the hammer - lol...and it has caused a couple of cars to chirp when I hammer it in said parking garage.
But, I've never had any trouble with the cops because I'm not an asshat with it.