For two 12W6V2 JL Audio subs in the back of a 156 saloon. For some reason on rap music my subs seem very boomy I think it's down to the box more so anything else. And really it sounds bad due to it not having low end thump if that makes anysense. It just sounds hollow. Is there any box deisgns out there that will fit into the back of a 156 and make it sound better.