I have not installed this yet -- in fact not even sure if I will go with the footwell, under the seat or behind the seat for it -- but this is what I am going to try. But I don't even have door speakers so this is really about filling in the midbass, not thumping bass.
Focal Integration IBus 20 Compact 75-watt powered 8" subwoofer at Crutchfield.com
