my experience may be just luck but i have driven my Buick around with a full 3" dual for years with no issue, my Z has a custom 3" ORY and can get pretty loud too but no tickets or stops as of yet (knocking on wood)
short of a cut-out they wont bother ya, just dont be stupid and attact attention and usually they will leave ya alone (few idiot cops withstanding, but thats any town).