I don't get any buzzing anymore from the rear deck at any temperature down to 30 (tested) so far, but I do get some other sounds that might be slight 'shifting' of the rear deck or something (anything on the ground seems to transmit right up into the car). Mostly, I hear that when on 'uneven' pavement. It's pretty quiet at freeway speeds now on decent road conditions.
I have heard some slight noises from what sounds like the passenger seat belt connection to the wall of the car and once in a great while it seems like I'll hear an odd noise from the front dash, but never more than once in a great while and then nothing. The rear wheels/trunk area seems a bit noisy like stuff is moving around in the trunk. I do have a small air compressor (that kind you plug into a car voltage outlet) and a couple of other things back there so it's possible they're moving or bouncing on little road bumps or whatever. I'd have to take them out to compare. In any case, between the fix for the door panels (they can still make noise with really big bass, but it's slight) and the foam tape on the rear deck edge and electrical taping the door strikers, the car is 500% quieter now. I mostly hear a tad of wind noise and the exhaust up until 85mph on the freeway and then the new Michelin Pilot Exalto A/S tires make a bit of noise above 85 (nothing too loud, but slightly noticeable above the other sounds. They're still wearing in, though). The stereo pretty much covers all those up, though, when it's on.