Here is some long awaited news on the upcoming limited slip differential option for the MCS. While it has specific pricing info for the UK market the rest of the information should be the pertinent to the rest of the world.

The Limited Slip Differential is a 30% differential lock which will only be available for MINI Cooper S Hatch and Convertible. For £100, this mechanical Limited Slip Differential increases traction, improves handling, increases stability and causes DSC to cut in later when specified. Please note it can not be ordered in combination with Automatic Transmission and will be included in the CHILI Pack for MINI Cooper S Hatch and Convertible.

Update: According to an internal pricing document from MINI the LSD will be available as a $500 standalone option in the US. BTW the option code will be 2TA. As mentioned previously, it looks unlikely that this will be a retrofitable item.