You can check the sticky post "SleeperZ Intake How To" for my personal recomendation.
That aside, any short ram intake for any Zetec will fit.
The actual cold air intake will need modifying as the Focus, Cougar, Contour do not have the same dimensions.
So required pipe lengths will be different from car to car.
An extra piece of pipe (or two) and an extra silicone coupler (or two) is all you'll need.
My attitude; buy one and mod to fit.