+1 for Chris Mayes. I bought my car through him only a few months ago and he was on my level in every way (as far as my needs for a 'drivers' car) and has a passion for the product. He is in sales though so I am not sure how much his influence delves into the servicing department, but he's worth a try. I believe he is currently on annual leave so you will have to catch him when he's back.
Have spoken with SoutherBM in the past regarding a Qualfe LSD install, I ended up getting information overload on how they build it and as such, demonstrated exceptional levels of understanding in their technical expertise.