How To Insulate Car From Road/Bass Noise?

I used the undercoating spray from WAlMArt (the can is red, long and has WHITE/ blue writing on it). I found it for $2.68 and $3.68 at different WalMArts. WORTH EVERY PENNY. This is just like the dynamat spray but for a lot less. I used 3 cans for the doors (spray the inside of the doors and the inside of the door panel). Road noise is gone (I habe 98 camry so it was not that bad but you could hear some before the spray). Shake the can before spraying (it is soopse to come out thick like insulating foam not thin like paint). Highly recommended product for trunks, doors anywhitng you want to insulate. I've listened to the quietcoat demo and I can tell you that the undercoating spray can deliver similar results.(1) Kenwood Excelon Head Unit KDC-X589 (24 bit Burr Brown DAC, 3 X 4 volt RCA).

(1) RF Punch 250A2 - running the components.

(1) Hifonics 6.5" Atlas Components (18db crossovers).