Not too experienced in the subject man, but I'm sure some of the experienced members will answer you soon. I'm also looking at a big sound deadening project on a somewhat newer vehicle, 07 accord. What I can tell you is if you think its quiet enough, don't go trying to eliminate road noise. Way more trouble than its worth especially if its a newer vehicle thats well built and quiet enough to begin with. But Yes definitely deadener on the door panels. Hit somewhat on the outerskin to reduce reverberation there, but focus on applying all on the inner skin (to what the speaker is mounted) to stop the vibrations and if going all out, cover all holes to block the back wave to have a significant increase in sound quality. You looking to run a sub or just amped components?