Silly is comparing a modified engine's output to a stock engine.
Modded RS7 4.0TTs put out about 700 hp, or still 150-200 hp more than a modded 4.2TT.
Also, the stock 2014 RS7 (first year offered in the US) was rated at 560 hp, not 513 hp:
http://www.edmunds.com/audi/rs-7/201...b-id=specs-tab