"No 850 has so much torque from a dead stop where one really needs LSD like true performance RWD cars do."

Frank makes a good point about this. *NEEDS* is the operative word, though. That's not to say that there wouldn't be some benefit to having that LSD in the car, but it still wouldn't be a cost effective improvement relative to the other places you could throw your money at.

For my money, some sticky tires would yield better results, especially if you're still riding on OEM-type, high-mileage, rock-hard-rubber Michelins like those that my car was delivered with. That upgrade largely eliminated the "hunting steering wheel" that my car exhibited during exuberant launches.

--
Jim Rothe, '99 S70 T5M,
http://www.jimrothe.com/volvo/index.html