[Limitless]

You can buy fatmat online which is a similar product to dynamat. Just take out your rear trims and carpets and put the stuff on. Time consuming but very easy diy. I have 2 layers of those all over the trunk and 3 layers on the doors of my 370z. Helps a lot with exhaust drone and other deep noises, if you go to Home Depot you can also get foam insulation and stick them in the same places to dampen the slightly higher frequencies. Only downside is that it adds quite a bit of weight (the fatmat/dynamat). After applying a bunch of layers it made the inside of my Z a lot quieter.

My friend just recently sprayed a few coats of this rubberized rust prevention thing on the underside of his fenders since he took off the fender liners for his widebody. Apparently he says that helps dampen road noise as well.

Road noise for the 370z sucks dick, gets worse when you change to noisier tires too..