Sounds like what you are hearing is mechanical noise, probably the subs bottoming out. Open the trunk and get even closer and it probably sounds even worse. Are all your settings cranked all the way up? Either way you playing it to loud and to hard trying to get more output out of it than it can handle. Turn bass boost down or off, properly set gain, and turn the volume down and it might not sound so bad. The bottom line is simple though, they are crappy subs in a crappy box therefore they are gonna sound crappy. No way around it bro.