This am I braved the heat and tackled the mudflaps: After removing the 3 fixings under the front wing the mudflap fitted pretty well except I had to open the holes in the mudlflaps to accommodate the original Ford fixings. The bottom one was a bit difficult as pushing the pin in is not helped by a flexible under wing protector.
The rear mudflaps needed no alteration but I used 10mm stainless steel nuts and bolts, instead of the Ford fixings as the under wing protector is a bit mobile and depends it seems on the 'spray' mat and underwing protector to be firmly fixed together hence the nuts and bolts.
The job would have been easier if the car had been on a ramp or axle stands as access under the rear is awkward when trying to fix one of the nuts on each side.
Having looked at the Ford brochure on mudflaps I honestly don't think there is much difference between the £80 Ford set ( if you can find them) and the £20 Xukey from Ebay.
Of course it is a matter of personal choice.