From my experience at TAG Motorsport, I would most definitely recommend NOT going there. The owners are very unprofessional, and there's lots of waiting, and you may feel you're getting swindled somehow.
For my Torsen LSD install, I went to a place called Driveline 2000. They're located in Scarborough, IIRC, around Midland and Ellesmere.
Anyway, the install price was very decent, and it was done on time. They seem to have quite a bit of experience with tranny stuff, and weren't phased at all.
Not sure if they'll pull the tranny for you... I just brought mine in after I pulled it out of the car.
Massiv.
