Sound deadener? Definitely.
 

Didn't know where else to put this, but I would definitely recommend installing sound deadener(I.e. Dynamat, FatMat, B-Quiet, etc.) in your car. Yes it's a little labor intensive, but all the interior panels come out very easily, and the cost & labor are worth it. I did my doors, trunk, the rear fender wells and behind the rear interior panels on the inside of the rear fenders. No more tin can sound! Less road noise, plus the stereo sounds so much better.

How much did it cost ya?

This car is quiet compared to my ITR so not for me....but curious, how much extra weight did this add? 50lbs wouldnt be too bad for a daily

I bought 50 sq. ft of B-Quiet deadener. It cost right at $100. It probably added around 20 lbs. total. You don't have to cover every square inch with deadener, just enough to break up the big expanses of sheet metal. I probably covered 75% of the big areas, like the inside of the doors, the curves of the fender wells, under the rear seats, the trunk, behind those dinky little rear speakers and along the sheetmetal around the inside of the rear fenders. I still have some left, I just need to figure out how to get the headliner out so I can put some up there.

When i get mine, i'm going to pull up the carpeting everywhere behind the front seats and use dry ice to remove the already present sound-deadener. I want as much sound as possible-- no more hotel lobby feeling as i drive. If i want to sit in a quiet place, i have a couch in my living room. Sound adds to the effervescent driving engagement. (IMO)

Well, when it's a daily driver it's gets old real quick...besides, when I want to hear a motor roar I'll pull out my 69 Mustang with the 408 in it. (: