Retrosound, Amps & Sub Install

A ported box, as shown in the picture above, would make the vibration worse as the port increases bass in the frequencies around where it is tuned, usually 3-6dB. Doesn't seem like much, but every 3dB is doubling the loudness. Your best bet is hushmat or dynomat or a similar sound deadening materaial. That sub moves air, creating pressure and will cause metal to vibrate. Nature of the beast. I have seen windshields crack, hair blow straight forward, tops of door frames bow outward... My old competition car had clamps around the door to keep the pressure inside.