03 sunfire, 2 12" alpine type s on a 600w amp. the subs are in a sealed box facing the towards the back of the car. sounds amazing inside, but when you step outside, close the door, all you hear is the loudest fucking rattle you could imagine. its not coming from inside the trunk, its not the hood, its not the bumper, its something coming from under/inside the car. the two things that come to mind are getting the trunk filled (someone told me this, what exactly does it do?), and also i still have the spare in the trunk which sits right under the box and from outside it sounds like thats where the really loud rattle is coming from under the car. so maybe if i take the spare out it will solve my problem?