When I asked my tuner he said yes. He said the aftermarket cats do change the airflow characteristics.. True or not. I don’t know. I ended up doing a few things at once so I needed a tune when I put on my new J pipe.. If you have a tuner your working with or plan to work with shoot them an email and go with that
Also looking into this same set up. Been online and what I found was if it’s catless definitely. Catted, it depends how many cells the high flow cat is but u might get lucky and not need a tune. To squeeze out as much hp and tq I would get a tune and to also avoid a CEL. Good luck.