A pair of Audi RS performance cars have been caught testing and show what the German brand has planned for these ultimate examples of the TT and A5. The TT-RS was snapped in production ready form and shows off some serious design tweaks including two gaping intakes flanking the already gaping corporate Audi grille, chunky fender flares at all four corners and a pair of large oval exhaust tips embedded in the rear bumper. Powering the TT-RS is expected to be a twin-turbo 2.5L five-cylinder engine producing between 350 and 390 horsepower, which will easily make it the fastest production TT ever.