What style box is it? Sealed? Ported? Bandpass? The best box for a sealed trunk application is Bandpass as it pumps out more air (bass). Another thing to do is to get some noise killer in a spray can, take out your carpetting and spray that **** all over the trunk until its sealed, leaving only the wall to the cab not coated, this will essentially force all the bass to the cab, and will also deter rattles within your cars body... I have found that Dynomat products work the best since that is what they are designed for. I have seen people cut holes in the rear hatch area or sometimes even in the rear seat, but I've never done that and don't think it looks all that nice. You may wan't to find a different place for that spare tire... I am new to the CarPC world, but I have a ton of experience with Car Audio.