12 w7 enclosure that will fit in a musta

Anyone know where I can pick up a prefab'd 12" w7 enclosure that will fit into a mustang's trunk?  I want to put in a slot-vented enclosure, I am already planning on giving up my spare (this is my toy car not my commuter).  I plan on building the system around the box, but I can't find anything.  Anyone have any idea's?  I really don't want to build my own, I would put together an unassembled on though.  Just don't want to mess with measurments and calculations, and I don't know how to tune it to 38hz either.

I don't know of any prefabbed ported enclosures specifically for the w7 but here one's that is sealed. http://http://www.subzoneusa.com/jl_audiow7.htm

This should work for your specific application, you just need to check the measurements: http://www.subzoneusa.com/zv_series.htm. The single ported ZV-121 is what you would be looking at, it's within JL's recommended specs. Personally I would build the box myself, JL includes a nice data sheet with schematics for a box with the woofer. I used the one that came with my 12w6v2 and got very nice results, building an enclosure is not hard if you just take your time and read up a little. The JL spec sheet even tells you what lengths to cut the wood and how many pieces you need, it doesn't get any easier than that! You'll also save a ton of money if you do it yourself.

y not fiberglass the whole trunk????? it would be easier... well calculation wise and it would use all the avaliable airspace