There's no such thing as too much horsepower.
John Hennessey claims to have the fastest CTS-V in the world, with his VR1200 model hitting 220.5 mph on the Texas State Highway. But SNL Performance, with the help of Karger, have created the world's most powerful Cadillac CTS-V, generating 1,309 hp at the rear wheels. The beauty of being a tuner is that you can concentrate on squeezing as much horsepower out of a car without giving a thought to how it will impact things like handling and reliability.
Taking a stock 2009 CTS-V, the tuners added a pair of Precision turbochargers to the 6.2-liter supercharged V8 as well as an air-to-water intercooler and beefier transmission. Along with other upgrades that was enough to more than double the car's 556 hp.