I have the same problem. I had about 18k on mine, and the passenger rear was completely shot. I put a fresh set of Pirelli's on the rear because I got a stupid cheap deal on two brand new rears from a buddy, and it's happening again. I've been told its either toe wear or the Torsen, but I'm not...
First time I installed the extremes I was like 'What have I done'. A year later it seems to have broken in, and I can slide into neighborhoods undetected. I'd say give it a bit.
Pardon my dumbass question amidst a sea of technical talk, but would the Torsen contribute to my right rear tire wearing out much faster than my left? Tire guy said it didn't look alignment related and that it was due to the diff.