I'm undecided. A lot of people have added it, but I haven't read anyone saying that it actually made a difference (aside from maybe killing off a rattle if you happened to have one). Because I'm doing this very casually and not as an audiophile I'll probably try without. If I get rattles, worst case scenario I take off the trim, unscrew the speaker, and put some in later. I'm really not sure how much difference it makes in this car otherwise; people still complain about boomy bass etc due to the lack of thickness in the door sheet metal. If anyone has experience to talk about the real world difference I'd hear, I'm all ears.