There's a guy over in the UK that's just done that (Decatted it), and ran an 11.3 in his S-Tronic spec'd car.
Looking at the exhaust system - it's all pretty good from factory!
2010 Audi TTRS (6spd)
Options - 19's titanium blades, Mag Ride, RS Seats, Bose, Extended Leather, AMI, SatNav, Xenons
Mods - Catback Milltek Exhaust, Wagner Intercooler, Self tuned - 343awhp