any subwoofer engineers out there?

[sixto]

Preferrably someone with no regard for patents.

I'd like to build a box similar to this -

http://www.taaffephoto.com/item_detail.php?item_id=109528

... for the 300D. I like the idea that air moves only into the cabin so there isn't more sound outside the car than inside. I also like that it doesn't take up more than 8" of trunk depth.

This unit was discontinued a couple of years ago. Some stores list it but don't actually stock it. And I just missed one on eBay. So I don't feel so bad about copying the design.

Any audio engineers out there who can spec a box and speaker for me? All right angles and round holes would be a plus given my lack of carpentry skill. 18" is the height limit between the trunk floor and hat rack.

Since I'm generally happy with the factory stereo other than the absence of bass, what I'm really looking for is something like this -

http://www.buy.com/prod/jvc-cs-bb2-120w-compact-powered-subwoofer/q/loc/111/202877083.html

... which fits nicely in the first aid kit channel of a 124. Kenwood and Blaupunkt make similar units but they're bigger and, more annoyingly, taller. The 2.5" tall JVC is easily masked by the first aid kit lid (which I can perforate). The 4" tall Kenwood and Blau units can't be easily masked. I mean it would be obvious there's something there.

I've heard one of these puppies and it belts out enough bass for my tin ears.

I've thought of upgrading to later door panels with speaker coves but that's more work than building a box. And the resulting bass might not be worth the effort :/

Thanks,
Sixto