I'll take a look at that putty knife technique. Gotta dig out the repair manual pdf again.
I'm hoping to get started on the permanenty upper grill block this weekend (Fiance is out of town and I need something to do while waiting on my Guino). But, in the mean time, since the weather is starting to turn colder I decided to work on the lower grill block.
Here's my highly complicated, extraordinarily expensive, and arduously laborious mod. Of clear packing tape.
Got about 75-80% of the opening covered including the license plate. When I do the real thing the open part is the same area I plan on having the "active" section. On this morning's commute it held up ok, coasting seemed to be better at highway speeds at certain downhill sections (increased speed vs maintaining in neutral) and the temps didn't go crazy (didn't hear the fan come on in local driving).
I didn't notice if it warmed up any faster than usual, but I'll keep an eye on it.