My 03' Cup now has 19,000 kilometers on her and it feels more squirrely under heaving breaking and turn in. I'm getting more wheel spin out of tight corners, but that could also be from getting on the gas too heavy.

So what torque spec should I be looking for when I test the diff, and has anyone had to rebuild their's yet?

 

I'd wait and see what the experts chime in with, but I'd say that the clutches are definitely worn out after 19K, especially with the symptoms that you describe.

 

You should be looking at a breakaway torque of around 50ft/lbs. The torque values vary depending on who sets them up. Street is around 25 and the new 997 Cup 8 plate is anywhere from 135-160ft/lbs.