If you want to throw money at something you never see then dynamat and liner is the way to go.
If you're like me and would rather spend the cash on something more useful the get frost king duct wrap from home depot. Way cheaper and you can double or triple up if you wanted to. And it works just as well as a sound deadener for doors and roof. I was worried about the roof pieces coming down but 4 years and gravity hasn't pulled it down yet
I have a single layer in the Charger and even on the hottest days, black interior, black top, dark purple exterior and cheap ass heddman headers, the inside of the car was/ is comfortable...... well, to a certain degree that is
On the sold Cuda, black int, red exterior heddman headers and no duct wrap.... Same hot days, the car was unbearably hot and basically only driven in the morning and the evening.
http://www.homedepot.com/p/Frost-King-E-O-12-in-x-15-ft-Self-Stick-Foam-Foil-Duct-Insulation-FV516/100028603