Hiya Robbie,
I hope this may be of help to you. I fitted a Pipercross ref no. PP -1620 to my Duratec engined 4/4 a couple of years ago. This is a panel filter and is a direct replacement for the ford unit in the filter box.The filter made the car a more responsive and seemed to free it up more than I expected .I am glad I fitted it, and for what it cost to buy it, well worth the money.
The filter for the 2 litre Duratec is listed as the same number for both 1800 and 2000 cars.
Regards ....Trodnik