Torsen goes in the transmission and makes sure you don't break your stock trans. from anything. It helps a lot with traction off the line and in corners as well. Sort of like the "takes power from the wheels that slip to the wheels that grip" idea. Take your time and search for everything I talked about above. The forums have been around for a while so you should come up with a ton of info. on what to get and what not to get.
