2017+ Models Audi RS6 RS7 4.0 TFSI V8 Twin Turbo Complete Engine

Audi Rs6 / Rs7 4.0 TSFI V8 550HP
I've recently bought a S6 with same engine as the RS and owner gave me this engine complete with the car. His story was he got told his/my car needed a engine (2013) out of warranty and a back street garage purchased it from Audi.