It sounds as if the Cosworth factory visit is for new ARP4 owners? I was told by one of the dealers who visited Cosworth, that the only difference in 225bhp and 275bhp is a pair of cams and some remapping.................. food for thought whilst at the factory?
Configurations and options:
http://www.cosworth.com/media/335568/duratec_components_catalogue_2009_v1.0.pdf 
