I guess we will never know Simon but that isn't a cheap moulding. Look at the low cost filter housing from fibre glass on the S1 Roadster. My guess is it is used by Ford on one of the many uses of the engine.
Moulds like this are also often made in pieces to make machining easier.I guess it is possible MMC only need a small bit rejigging.
Or, in the case of the airbox inlet, rough modification with a hacksaw!
