Honestly, along with the KWV3 coilovers, the OS Giken LSD was the best modification I did to my car.
The first time I took my car on a nice canyon road (Palomar Observatory) I realized how much better and stable the car was coming out of the turns under hard acceleration and heavy breaking, it was a completely different car, just awesome.
I believe that OS Giken recommends you to replace the transmission oil after the first 500 miles or so as the plates will be "seating" among them selves, if I ever get a newer Cayman, this would be the very first mod!