As far as I know, there's only one off the shelf dual-exhaust for these cars, and that might need some additional modification, too. It's not real cheap either. That would be the Hooker Blackheart system.

https://www.holley.com/products/exha.../70501426-RHKR

summit do a cheap duel system

As a thirdgen goes, if you have long tube headers you will probably need to fabricate the center section and have it connect to an off-the-shelf section from the rear axle back. Your best bet would be to look up and save as many pictures you can of member's exhaust and take those to an exhaust shop so they know exactly what to do. No standing around head scratching necessary. then they just connect it to the rear portion that you brought them.