From listening to your Borla S's, my opinion is that they sound significantly louder, but also a little
raspier (higher pitch) than my Ford Racing Touring Axle-back Mufflers (which I understand are basically the GT500's, except with rounded tips).
Here's a clip of another
GT with Ford Racing Touring's. You'll get the idea. Comparatively mild and unabtrusive at start up and under normal cruise...but with a nice "grumpy" low end sound, which develops into a satisfying howl under WOT. Just perfect for my needs. 2011 Mustang GT 5.0L Coyote Ford Racing Touring Mufflers M-5230-MGTCA - YouTube
IMHO, neither is "better", it's just a matter of preference. BTW, nice car!
2012 GT Yellow Blaze MT 3.73 * Steeda CAI & 91 Tune * Koni Yellows * Steeda Sports * BMR Adj. Panhard Bar, UCA, LCA's & Brackets * Barton Shifter & Bracket * Ford Brake Duct Cooling Kit * Steeda Brakes * Hypersilver Eurotek O2 19x9.5's * 275/40ZR19 Michelin PSS's * Ford Racing Touring Mufflers * GT/CS Front Valance * Boss Splitter * Blackout Fogs, Deck Lid & MMD Tail Light Trim * GT500 Rear Diffuser & Splash Guards * Infinity Ref. Fr. Speakers * Custom Faux Gas Cap * Redline Hood Struts *.