here in rhe wet side of washington state the cops are kinda anal about having an exhaust system on your'e vechicles. the law here is stated as;
"ALL vechicle exhaust must exit past the last passenger compartment or to run in such a manner as to direct exhaust away from the vechicle."
washington state law has parts that also mention mufflers MUST be used as to quite the DB level.
problem with the DB part is most cops have no meter to measure the loudness and just guess, so if ya get a noise ticket it is really hard to fight.
the po-po's here write big tickets for not having good exhaust on your'e car.
there's some towns that have a lower DB level than state standards and will write ya an invite to the local courthouse if'n it's to loud.
Later[ddd