I believe there are few difference between a 4/4 and a Plus 4 Duratec of that age.
These are the ones that I know of :-
The cut of the wings to suit the tyres determines the width.
The diameter of the bore in the block to reflect the 200cc engine difference (the bore/stroke is square on a 1.8).
The diameter of the inlet/exhaust valves.
The 1.8 has a throttle body mod to prevent the butterfly fully opening to limit performance (that can be removed
).
And a huge price difference!
I’ve fitted the Mulfab panhard rod with no problems to my 1.8.
