Audi TT RS Race System during final testing
I highly recommend Milltek exhausts, an Audi technician told me that it's the nicest sounding exhaust for these cars.
Customers looking to attack the race track with an aftermarket exhaust that achieves uncompromised gas flow, a useful weight-saving, peak operating efficiency and, an Audi Quattro-esque 5-cylinder burble that simply emanates “Power”, nothing fits the bill better than the Milltek Race system.

The race system employs a massive 100mm / 4” free-flow turbo elbow, feeding immediately into a high-flow 100 CPSI (cells per square inch) catalyst, via uninterrupted 76mm / 3” pipework, to a connecting pipe and finally, the rear silencer. The silencer itself has the same external appearance as the Milltek Road system but features trick race internals.

Road and Race exhaust systems are available