Maybe "strut bar" isnt the best way to describe this device. Typically a strut bar is used on a unibody car to tie the two strut towers together and sometimes to the cowl area. For anyone who doesnt know, in a unibody type car the suspension components bolt directly to the cars body and the body itself is a structural member acting like a frame. The Kappa is a body on frame type construction where the body is essentially non-stressed and the frame is the mounting point for all the suspension components and the powertrain. Opinions vary on the superiority of each but typicially unibody saves weight but has some trade-off reguarding rigidty. That being said, Porsche seems be able to make the unibody set-up work real well.

As far as whether or not this particular product is worthwhile, it does seem to bolt to the frame rails at least somewhat near the suspension pick-up points so I suppose it couldnt hurt. Whether or not itll be a noticiable difference, seeing as the frame seems to be pretty stiff already I personally doubt it'll do too much.