Audiophyle's system:

1988 Honda Accord LXI (240,000 miles, just getting warmed up)

Nakamichi CD-700 head
Alesis MEQ-230 EQ
Nakamichi PA-506 amp
(2) 10" Oz 250L 10"subs in 2.15' spare tire well enclosure, SEALED!!
(2) Focal 5KX 5" subs in .18' aluminum boxes welded into front doors (no buildouts!)vented, boxes tuned to 48Hz
An A/D/S/ 320Is component set in the Kickpanels, mids are in vented enclosures, tuned to 70Hz.

channels 1/2 of amp run component set, using crossovers provided by A/D/S/, high passed 70 and up

channels 3/4 run the Focal subs, in stereo, bandpassed from 20-110Hz

channels 5/6 are bridged to the subs, 55Hz and down.

No capacitors. No extra batteries. No electrical mods. No BS. K.I.S.S. was employed in system design.

Car is EQ'd out to 2Db increments between bands, and no single band has more than 4Db of gain. Had to cut more than I had to gain actually, very strong midbass.

Install is still not complete. They never are. It's not even up to show quality, except for SQ. Need to find some time and extra cash to get install completed.

As to total system cost? I shudder to think. Good thing I didn't get the Nak outboard DAC... YET!