Ever since I fitted some new Infinity 552s in the front of my car, the left one has always rattled when the bass got a bit heavy. I tried Dynamatting the inside of the door and this made a bit of a difference but the noise was still there. Well today I got really p*ssed off with it so I decided to put some small pieces of dynamat on each side of the lobes that you screw through and its fixed it!!!!
i can now crank the bass up and wear a baseball cap on backwards without worrying about any rattles! lol
Rick