My personal opinion is anyone running open exhaust on the street is irresponsible. I have no objection to an exhaust in keeping with the character of the car, but that can be done without running open exhaust.
Moving from stock exhaust manifolds to headers will increase the exhaust note, as will moving to side exit from rear exit. Are your current mufflers / resonators rear-mounted and, if so, how much room do you have under the car for mufflers if you're running a side exit? I've heard some folks have had success running Spintech mufflers. They have a line of low profile mufflers that may work where others don't.
https://spintechmufflers.com/mufflers/
FIA Kirkham with Spintech:
https://www.youtube.com/watch?v=CoWTU90anG4