My 997 C2S was a fine road car (although a little unstable at 250+ kph in sidewinds and on bumpy autobahn sweepers). When I started to track the car, however, its limitations were immediately apparent.

So I changed to a 996 Turbo with H&R coilovers. After lowering, this car was stable at 310 kph and was great at everything except prolonged track use (too heavy).

My next car will be a CSL or a 997 GT3; these cars are stable at very high speeds and light enough for extended track use. But there are some reports of GT3s feeling unstable when encountering bumps in high-speed sweepers.