This option is the addition of the "shock/spring", not a replacement, you just add it to the suspension as a supplement; it's not a "coil-over" as you're thinking like the MBT and other set-ups out there.

My point is, if Porsche didn't remove the torsion bars then neither should you. The rear coil-over is "neat" and it's "pretty" but it's very very dangerous because the entire weight of the rear of the car rests on that one bolt (on either side). I would not feel comfortable driving a car that if one bolt was to break something like this would happen.