well going back to my boy racer days... when I swapped out the speakers in a vw polo 6n for components... I used dynamat... but i noticed something special about it... it actually reduced road noise by quite a bit... and I shoved extra dynamat behind the glove box too...
under the bonnet... i brought a thick piece of fire proof sound deadening (also helps to keep moisture off engine components)... cannot remember which site from but i had a mechanic rivet it on... why did i do this? my tappets were knackered and this masked the problem and me feel good as a little boy racer...
side thought... and I am no expert on this but I wonder if it would be possible... to change the engine mounts to lessen the vibration..may be some kind of flexible engine mount pieces?
Read something about active vibration control a few years ago... think it is where the engine sounds are taken into a microphone or something and directed elsewhere but i may be talking out my bum on that one.
