so i got my system yesterday well the rest of it and i was bumpin and as soon as i would turn up the volume alittle bit i would hear this ear pearcing slap sound it was coming from the back so i put some like wheather stripping foam around the back deal that holds in the 6x9s as i thought it was the light slapping against the rear window but no that wasnt it. so then i thought oh its the 6x9s poping and slapping ya know just bottoming out. nope that wasnt it becasue i unhooked them and it still did it so i ended up just straight up taking the 6x9s out and that was it it was building too much pressure in there and pushing the 6x9s flat. so now its all bass in the back and trebble in the front ill fix that later though. just thought i would let you guys know if any of you have this problem.