not sure your budget, but I would go with Borla Atak. I have this set up on mine and one if the best sounding I have heard... Wheels and tires. it all depends on the look/style you are looking for. Americanmuscle.com has a great selection of wheels and tires with packages.
2015 Saleen 15-0030 White/Black, nav, Saleen package, 20" 5 spoke Carbonite wheels, Borla Atak, S4 full supension upgrade, recaro seats, Brembo big break upgrade, soon to be full carbon kit, plus soo many more.
2012 GT Preimum, Silver/Black, Nav, Boss Manifold, Throttle body, Airaid intake with tune, Bolra Atak exhaust and long tube headers, 20" Black wheels, GT500 spoiler. Eibach Sport Pro shocks struts and springs, Ford Racing Swaybar kit, Whiteline Panhard bar.