Alright so instead of using traditional deadener on say, for example, my doors, I was wondering if I could just use several coats of fiberglass to help fight both rattle and flex at the same time. On top of that I maybe put some bed liner to just add some extra rigidity, and then on top of the bed liner some spray on rubber to make the surface a bit more absorbent so my mids don't sound weird. Now, the question is, how will doing this to my doors affect my resonant frequency in the vehicle? The reason I ask this is because for my setup I want to really focus on low end, and as it stands the vehicle I'm looking at (pathfinder) tends to be very peaky at 50-60hz. The last thing I want to do is increase that peakiness.
tl;dr Will using fiberglass instead of traditional deadener increase my vehicle's resonant freq.?