If you want good bump, you will have to get an enclosure. I had a 4th order Bandpass enclosure w/400watt amp in my Avenger trunk, was VERY bumpy... Door speakers, even with long throw speakers, are not going to produce the deep & rich bass you want. Bandpass enclosures are about the best for the best bass.
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Mine was like that, but with THREE ports.
http://www.sonicelectronix.com/cat_i212_12--bandpass-subwoofer-enclosures.html
The thing with bandpass enclosures, is though they sound great, and can most definitely ruin your ears; they require more power to drive the speakers in them, almost twice the amp power. The speakers are IN the enclosure, sealed behind Plexiglas. You only have the ports that are exposed. The amp must also have the cut-off, so that only 350Hz and below are sent to the speakers. I would maybe even go 250Hz and lower, some are adjustable. They sound just HORRIBLE if you try and run them without a crossover, or cut-off built into the amp. These bandpass enclosures are built for one thing only, and that's defining bass with the right amplifier.