For a Torsen the spec would be torque bias ratio. The lower the torque bias ratio the less torque transfer can occur. 2.5:1 is common. Generally speaking the lower the torque bias ratio the more the diff acts as if completely open. A lower TBR is better for road use.Yes, this is the base difference between RWD and FWD.
Back in topic, as I understand Giulia has LSD with no more than 25% lock. It's done for better traction in a fast slippery curves, not for off-road.
Good winter tires are always helpful in a winter, with studs are even better. It does not matter what type of traction car has, tires are the key.
Sent from my Z957 using Tapatalk
The BRZ is reputed to have a high TBR and can be a handful in slippery conditions as the torque can get pushed back and forth across the axle quite rapidly making it tricky to drive straight. On dry road this makes provoking a drift easier which is why I think Subaru/Toyota chose the higher TBR than would be ideal.
Mechanical clutch type LSD vary the degree of slip permitted before lock up by selecting different angles for the torque reaction pin to slide in, usually different between drive and overrun also. Initial slip resistance is set by internal spring pressure (Belleville washers) Wear can be severe if very grippy tires are used.