Jim, the Quaife applies power to the wheels very much differently, than the oem setup. It's pricipal operation is different, and it is said to give a little better of the line traction. Where is really shines is when going into a turn, and accellerating. The power percentage is shifted to the outer wheel, instead of the inner wheel. This keeps the car tracking much better than a posi style. As a matter of fact it a life saver in this respect. No car on the track can keep up with a Quaife style diff.
As far a feeling the benifits on cornering, well I'm scared to death to accellerate hard enough on a turn to ever notice it, on the street that is, but come the day you do get on it when the car is not straight, you will benifit from it. I would also say the car is much less squirly from a hard take off.
Cost to swap out the redone unit is very low. It's the build up that cost.
The Hydro Lock unit is not a true torque sensing diff. That's what Jerry from Unitrax told me, and he doesn't even sell the a torque sensing unit for the SRT, so I'm inclined to believe him. Hydro Lock is just a different principal of operation, but still functions as a Posi unit.
Wheel hop may be reduced with this setup, but there are many factors to wheel hop.
Skip White