GT2s excepted, the 964 was the last widowmaker 911 Turbo. Lots of power, lots of boost, and trailing arm rear suspension made for a much trickier Porsche than the 993 Turbo which followed. Even stock, this is a car that wants you dead. As they say; the closer you are to death, the more alive you feel. Of course, the best approach to modifying such a car is to nearly double the horsepower. The video does not specify which 964 Turbo variant this started life as, but this build brought the already-intimidating base Porsche from somewhere between 316-380 horsepower to a full 600.
The engine was originally built by Andial for Jeff Zwart's 1994 Pikes Peak car (which can be found about halfway down this page). While Andial is now defunct, though Porsche did purchase the name, the company left no small mark on motorsports. Victories include a 1994 class win at Pikes Peak with this motor, plus class wins in 1996, '97 and '98. Andial cars have also won the 24 Hours of Daytona (including powering all of the top 5 finishers in 1987), the IMSA Supercar series, SCCA World challenge, and more.
That level of development and provenance propels a 964 which is seriously impressive on its own merits. The builders shaved the roof rails, which is no small job on an air-cooled 911, deleted the heat and A/C, and replaced some of the glass with Lexan. All-told, the 600 horsepower, CIS flat-six has just 2,800lbs to motivate.
Of course, because of the old-school CIS injection, the redline is limited to just 5,800RPMs. With the amount of power this Porsche produces, I'd guess few will miss the extra revs.