The original Targa contained a structural steel roll bar which increased torsional rigidity. Does anyone know if the new Targa roll bar is functional? Has anyone seen the specs for Torsional rigidity of the new Targa vs coupe and cab?

 

Porsche has said the Targa has the same rigidity as the Cabriolet, and both loose quite a bit to the Coupe as you would expect. That said, unless you are tracking the car with sticky R-Comps and aftermarket suspension, you are likely not to see much difference on the street. There are specs out there on the 'net, in Porsche Technical papers, but I don't recall them offhand.