Thyanks Gaz,

Very informative.

The programming part sounds a bit complicated.
I would obviously go for the 115 and avoid the trouble but the road tax is about £40 cheaper per year for the 100 here in Malta. If it was as simple as replacing the Ecu it would be quite tempting.

Regarding the number of valves,
I have an Autodata cd rom with all the data of most cars.
When I looked up Ford Focus or Transit Connect, there were 3 types of engines.
a) 1.8 Tddi
b)1.8 Tdci
c)18d

When I looked up the 3rd one and looked up 'timing belt renewal' the diagram showed 2 camshaft pulleys (DOHC) and this type of engine is chain driven not belt.
Has anyone ever heard of this engine? The program gave me all the data on this engine so it must exist but I've never seen it on a Focus or Connect.