Both rear and all wheel versions of the Porsche 996 started out with the 3.4 liter flat 6 engine in 1999. The following year, the 3.6 liter twin turbocharged engine would be introduced for the all wheel drive Porsche 996 Turbo. That engine made 415 horsepower and could propel the 996 from zero to 60 miles per hour in just 3.9 seconds, a time that's impressive compared to other exotic cars from the likes of Lamborghini and Ferrari.
There were two lightweight versions of the Porsche 996 made for performance, named the GT2 and GT3. These were six speed manual transmission cars that lacked some of the luxury features of the standard 996 in an effort to drop as much weight as possible. The GT2 was a rear wheel drive car that had a specially tuned version of the turbocharged engine from the 996 Turbo. It made 477 horsepower and could get the 996 GT2 up to speeds near 200 miles per hour.
The Tiptronic option on the 996 allowed the driver to switch into manual gear shifting mode for a period of 8 seconds before the car would automatically switch back to automatic. This allowed for selective shifting on those tight corners while giving the car the chance to change gears on those boring straightaways.
There are plenty of these out on the exotic used car market today. You can find them at Porsche dealerships, but you'll probably find better deals if you just look on eBay.