Steering uneven

Hi Everyone,

Problem on steering. I have a 2006 Porsche 911 Carrerra 4 (997) (4 wheel drive). Since day one, the steering has been uneven meaning that it is “looser” or has more give when I turn right and is “tighter” or more responsive when I turn left. The alignment is normal and straight. I’ve brought it back to the dealer 4 times and they’ve changed the steering rack but say there’s nothing else more they can do. This has been extemely frustrating b/c its makes it unenjoyable to drive a sports car b/c of this difficult handling. I dont’ know anything about the steering mechanism of Porsches, esp. a 4 wheel drive system but I’m thinking could there be a problem in the steering column? What else could I have them look at or demand to replace? Thank you.