The WRX isn't the loudest car I've ever had, but its making a few DBs at normal crusing speeds ie. >125 I put Dynomat on the backs of the rear seats, made a new fiberboard bottom for the trunk. There is a reason they make it smaller but it's a great surface for the dynomat (on the shiney side) And did the sides of the trunk to the best of my ability without hacking the sheets to death. How flat are the insides of the door panels? And if anyone had their WRX undercoated, was it a drastic noise reduction? Also could I get a layer of Dynomat under the carpet?
Hey just FYI I did all 4 doors today it took almost all day but I got everything back together and I only said "where the hell does this go?" a few times. But the improvement is wonderful. I will say it makes the wind noise a bit more pronounced, but at 70 its much more quiet inside.