I live in Grand Rapids, MI and visited a local Foam manufacturer. In their enormous warehouse, they have a small room filled with scraps. so I went through and found the highest density, most thin foam. spent $15 and put it in everywhere. I found the stuff worked awesome. I've tried Dynamat but the stuff can be expensive. For $15 and a bit of searching it was well worth it to me.
2000 White 2WD Ford Ranger, White Tonneau Cover
Replaced Headunit with an Alpine Stereo and Alpine 5X7's in front and 6X9's in back, 00' Explorer Leather Seats to Automatic. Black Headlight Covers, Black Headliner, Blk/Gry OHC, going energy efficient with LED's and HID's, got sound proofing foam @ a local manufacturer and insulated everything (no sound or road noise)