It's a little more complicated than a bolt-on booster. Called the HPE1000, the turbo kit has stainless steel headers and down pipes, billet aluminum compressor wheels, and a high-flow air system. There's also an an improved fuel pump, and the engine and chassis are specially calibrated. You also get numbered plaques signed by John Hennessey himself and the engine tech who builds your mill.
All of this helps get your Hellcat to 60 miles per hour in 2.7 seconds, and it can do the quarter mile in 9.9 seconds at 142 mph. The Hellcat and it's 6.2-liter blown Hemi V8 are not for the faint of heart. Hennessey makes this Dodge downright demonic.