They are probably installed under vacuum and when in place sealed up. You could do it yourself with a shop vac. Used to pack clothes in luggage with trash bags for space saving. Amazing how much air space they take up.
Plastic and Foam Bag in Engine Compartment
Had read on some other threads about the foam with plastic bags, that were ripped and full of water. Well I checked mine and one is ripped and full of water. Wondering if Ford will fix and replace under warranty. Looks like they ripped the bag when they were jamming it in the space 
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