Installing a high flow catback exhaust is a quick way to pick up horsepower and torque. A catback exhaust will also give your Audi TT/TTS a sportier tone. All Milltek catback exhaust systems feature a bolt-on design and mate seamlessly with your factory or most aftermarket downpipes. Milltek Sport exhausts are produced in high quality type-304 aircraft grade 3" stainless steel tubing. This material is anti-magnetic (other manufacturers' stainless steel may not be) and is less susceptible to discoloration. This quality of stainless steel is used on all pipework and the total construction of the silencer. Mandrel bending ensures full flow bends for better gas flow and Milltek systems are increased in bore to ensure ultimate performance without the loss of mid-range torque.