my sub sounds really bad
 

i have 1 12 inch W3 running from a 250/1 jl amp. On most of the songs i listen to, the bass sounds like crap, since it makes an annoying banging and rattleing sound in my hatch. It does it even at low volumes. It is def not blown, and i doubt it is distorting, since i can have the volume at like 3, and it still makes a weird bang and rattle noise. I know it has nothing to do with sound deadning, since my friend has a camaro with 2 12 inch W3's in it. His car has no sound deadning whatsoever, but it doesn't bang around and rattle in his trunk. Must songs sound like this in my car, which the acception of some songs like cot-damn by clipse. It sounds weird, but some songs sound amazing like cot damn, but songs like, "its my party" by fabolous sound like crap. Please help me. I was thinking that my gain was too high or something, but i have no idea how to lower it on my jl audio amp. Thanks guys.

Sounds like your enclosure. What kind to you have?
B.J.