Hi Sean.
Recommended.
Essex ...... Xtreme Scoobies
http://www.xtremescoobies.co.uk/
Recommended
Middlesex .... Power Engineering
http://www.powerengineering.co.uk/acatalog/home.htm
I can't recommend slowboys but one London member said Slowboy's are very good.
South east London .... Slowboy
http://www.slowboy-racing.co.uk/