Old thread, but happy to have found this thread... I had been contemplating making some sort of radiator shroud extension/deflector of my own, when I stumbled on this thread. Found the "OEM" parts on "PartsZilla" for less than $25 shipped, so ordered the deflector, rubber flap shield, and all "OEM" clips/fasteners.
With no instructions included in the shipped parts, this site is where I turned to for thoughts on how to install without taking the front tupperware off, and happily found this thread.
Started by removing the driver side front shock & tire, then slid the coolant recovery bottle up and out of the clip and temporarily zip-tied it to the front bumper.
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AND, then discovered no holes in the c/mbr of my early 2016, so rather than trying to squeeze into the miniumal space with my angle drill and drill the "called for" holes, I instead drilled an additional three holes in the shield that align with the original holes, but directly below them, at where the lower edge of the c/mbr would be. I then used two zip-ties per hole to secure it in place.
IMHO, it's as solidly mounted as it would have been, if the holes in the c/mbr and the OEM clips had been used. Total job start to finish was less than an hour, including putting tools away.
And the best is that even with our 100(+) degrees here, it's significantly reduced the temp of the air coming through the instrument panel...