At least now I can hear myself think...

[jbcollier]

https://jbcollier.smugmug.com/Lotus-Europa/i-pdQZ8tQ/A

I can't hear cell phone rings (mine's not loud) or tones but I can hear the signal flasher clicking!  Still not going to refit the radio though.

[andy harwood]

That looks good, and good to know it works.
I had tried some rubber sheeting and closed cell foam, but really didn't seem to work well.
A P.O. had filled the sills with the can foam. Great idea. In practice, took me about 3 hours to remove enough to fish out what was left of the seat belt anchor plate.
Eastwood sells their house brand of the same style stuff, but the reviews are not so good.

Your car looks great!