Although Lingenfelter Performance Engineering performs its magic on a range of GM vehicles, as well as the occasional Viper, it's best known as a Corvette shop, and its reputation is more than justified.
If you give LPE a tidy $45,995 plus your Z06 Corvette for two or three months, you'll get back a fire-breathing balanced and blueprinted 427 cubic inch, 800-hp, twin-turbo monster, complete with dyno reports and a 2 year/24,000 mile warranty. Yep, 800 hp. (The LPE website has a video of a twin-turbo C6 'Vette pulling over 1,000 hp in a dyno run.) Full details on the Z06 engine package here.