Well Illusion,
I'm sure your components are plenty good. There is only so much bass you can get out of a 6.5" speaker. Maybe it's time to replace your sub and/or amp. One of these subs in about a 3cu ft box with a 300w amp will only create new rattles, but you'll won't hear them anyway

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http://www.partsexpress.com/pe/showdetl....t_ID=7765&DID=7