These guys are based in the West Midlands and I can recommend them personally as they recently serviced my ST, fitted a new intercooler and then MOT'd her for me!
Their service costs were very resonable and I felt confident that my car was going to be well looked after and it was :) I'm extremely fussy where I take mine ;)
They also have a very drool inducing range of Scoobies and Evos in their showrooms and do specialise in all rally/performance motors
http://www.xtreme-uk.net/