Just saw your location as Newbury and advised Bulldog. I have been using them for years now and they are amazing. You know when you get all sorts of Impreza's and WRX's parked there for service, that you are in safe hands. They can deal with stock cars and modded cars with the same ease and enthusiasm and you get to see these Prodrives or Cosworths as you drop and pick your car. What's not to like?
They also charge just 1 hr 15 mins labour to change spark plugs as they have the right tools to deal with boxer engines and do it day in day out.
All in all, I highly recommend them!