you sure your hearing a rattling trunk?...there will always be rattles from a trunk/hatch...im leaning more towards your back deck rattling...mine did that in both my cars, on one i pulled the backseat off the hooks thats connected to the back deck, and the other ride i cut a port in the middle of the seat, so its like a direct bass port towards the front windshield....both will work very well...but if think its the trunk rattling, tighten the trunk/put some dynamat in it...the trunk rattling shouldnt effect the way the bass hits unless your trunk is EXTREMELY loose..thats why im leaning more towards your back deck...what kind of car do you have, that'd give me a better idea on what to tell ya