Retrosound, Amps & Sub Install
i'm guessing that you need a port hole & that would stop 75% of the vibration.
right now, your kicker is in a sealed area. there needs to be a place for the air to move in and out in relation to the movement of the woofer.
without a portal for the air to travel to/from the passenger space, (or outside of the car) you will cause major vibration.
you really can't put a portal to the outside of the car without letting rain into the trunk. so i'd recommend a port that opens between the trunk area/pass area. you will need to be creative.