I am attempting to make the bass output of this system more robust by enclosing the rear parcel shelf mounted speaker. A local auto sound tech. says that it is unusal now to use the trunk as the box, as is the case in my vehicle ('94) and proposes bulding an eclosure. I suspect I can do this myself and avoid his 250.00 charge. Has anyone found bass wanting on this system? Short of replaceing the system, what have others done? Thanks.