Thanks for the quick reply and great picture. I tried to depress that tab but was afraid I would break it. I solved the issue by taking out the two screws in the map lights mounting and removed the mounting with the bulbs in it. I was able to remove the cup that the bulb plugs into from the back and replace the bulb there, then just reassemble. This eliminated messing with this defuser. Thanks for the link to the LED site. I will order these and change all lights out, yes with the temperature you recommended. I don't like the ultra bright blue tint of the higher color temperature.
I just purchased a 2005 red roadster and am going through it. It only has 37000 miles on it so actually I am just tweaking all the little things.

Regards, .