It's a whole different beast. More like Skyway, but you can use both lanes; but about as narrow. Crazy elevation changes and camber. Having to watch the mirrors the whole time really affects your concentration, too. 129 feels a lot longer. 'Ring speeds can get really high, brushing 130mph (not in the straight) in a moderately powered car.

Basically, we've all driven backroads fast, and that prepares us for 129. We're generally not topping out 4th, passing on the outside of sweepers and braking into decreasing radius turns. You go to the 'Ring completely unprepared.