There is a HUGE difference between a full catback and a muffler swap.
Specific to Borla/Corsa/Other high end catbacks, the biggest improvements are:
- Full T-304 stainless steel. This is a MUCH better and longer lasting material than the 409 grade factory stuff. It is also extremely rust resistant
- 3" exhaust from the cats back vs factory 2.5". More flow, more power, more sound.
- Nice tips that will fill the gaps in the bumper much better than the factory
Just doing a muffler is fine for sound, but if you actually want to improve exhaust flow and get the full on sound out of an exhaust, a catback is necessary. More expensive, but compared to a muffler swap it is apples to oranges.
Also you may want to consider drone in the cab. Some like it, some don't. My wife absolutely can not deal with the resonance many exhausts cause so I had to spend the money on a Corsa system as they are the only company that guarantees no drone in the cab.
Just some advice from a guy who has bought more exhausts over the years than he cares to remember. Lol. Best of luck and the Borla's do sound great...the S-Types are usually a bit louder in person than expected. I had the ATAK on an '18 F150 with the 5.0L and it was ridiculous. The neighbors HATED it.