[seningen]

If its not the shifter cables -- it could be the fulcrum pin(s), common for us Spec Boxsters, but I haven't heard this from the general populace, nor with 6 speeds.

I had something similar on my S (track car), and found one of the tiny pins on the shift linkage internal to the tranny had fallen out -- there are 6 of them, about $6 total. I think my mech fixed this just splitting the back of the tranny.

Mike