I had both buffeting and low frequency resonance and they are not related. You can actually feel the buffeting if you sit in the cargo space and touch the rear glass on hatch while someone else is driving the car over potholes etc. Vinyl tubing fixed that, and no amount of rigid stop adjustments helped before I added vinyl.
The low frequency resonance comes from metal panels and wheel wells and you need to add butyl and maybe foam to fix it (I added both). After fixing both, I took 600 miles trips with no ear pressure or headache. It still not a Lexus and has stiff suspension but I am not committing to coilover yet.