I'm driving a convertible so there is a certain about of squeaking that you have to live with due to the convertible top. And with the top down, the wind noise is impossible to get rid of :-0.

However I do know people with convertibles who mounted Dynamat. I know one guy who works for a radio station and was able to get a lot of the sound proofing material for free from the radio station and decked out the innards of his Miata with it.

Calvin