Laust Pedersen

Talking about Audi, they certainly do know a thing or two about turbocharging. Their A6 RS6 (V8-4.2L, twin turbo) has 413 lb-ft from 1950 to 5600 rpm, flat as a board (450 HP @ 5700-6400 rpm) found here . How do they do that? Relative large displacement, high compression, low boost, perfectly matched turbos, all of the above?
Very enviable.