Thanks for the advice, but i think i am going to leave those holes as is just for servicing, i think if i cover the areas near them, it will be good enough. In addition to sound improvement i am after door which dont clunk, less road noise and less noise from the window mechanism. I have bought dynamat extreme stuff which is lighter than original dynamat and does not require heating before installing. So hopefully door wont be that heavy.You'll want to use it on the outer skin of the door to make it a "heavier" sheet of metal in order to give is a lower resonance frequency hopefully outside the audio bandwidth.
BUT you'll also want to use it on the metal under the doorcards. This is full of holes for servicing i.e. the electric windows making it useless as a speaker chamber. Close as many holes as possible. You should close the bigger holes with i.e. alu strips rivetted as bridges over the holes on which you can stick the dynamat to make the big coverings stiffer.
You will notice the difference but it will make the car heavier Goodluck !