I know sussex dyno tuning are pretty good in horsham, the other half works there and they have done a fair few cossies since shes been there althou they specialise in jap aswell, and do it all on a rolling road.

Will be taking mine there once ive run it in to get it all set up etc!!!

Julian godfreys are good too but their pretty busy the begginning of next year and set their cars up on the road so dont like doing it in shitty weather!! spoke to them the other week for some advice as they had worked on my car in the past.