Then again, if you do that, why no just try a baffle board and mount a 12" sub infinite baffle? - I can almost guarantee you it will sound awesome and will be able to have the flattest frequency response of any set-up. It'll even be "punchy" as long as you use the right sub. JL Audio 12W6 for example, is known to be great in that set-up. You would only need about 250-350 Watts or so to run it.If you have them build it so it fires through the ski-pass (front of box sealed against back seat), then you will have no trunk rattles because no sound waves will enter the trunk. Easy and effective!