What a lovely fox! Yeah, I think mods are a given. 3.73 is a nice starter, One could argue for 4.10s if you're sticking with your current combo. Sticky tires. Blow up the T5. Then T56 magnum, or swap with Cam's and make him a deal. I see a blower or nitrous in your future, too.
I predict you'll sell your S550 inside of a year, now that you are about to experience the pinnacle of Mustang generations.
Also, show these boys the rig you picked this car up in, including the tow vehicle.