Friendly MOT stations :
For everyone Based around Chelmsford area : This is the Place to go:
Spantec Limited in South Woodham Ferris (Eastern Ind. Est. )
They don't care at all about race cans - in fact they love them 
And even if it has "Not for road use" on the can - I quote:
"Just put a sticker over it or grind it off"
They also Service any bike there...
Other MOT Stations:
Chelmsford
J. Pease - no race can allowed
Hadlers Garage - no race can allowed
Southend on Sea
Harley Davidson Dealer
They don't give a **** about what mod you have on your bike
Sudbury (Acton)
R'S Autos LTD-
Don't care about race cans as long as it does not say "Not for Road use" in big letters on the Can. Very friendly there!
Maidstone
Laguna Motorcycles -
race can allowed, very professional service there! + Great Range of clothes!
Will update this post as i visit more dealers..