The signal starts with an Alpine CD Tuner (CDA-7832) with 4-volt output and a wireless remote.  A Precision Power Crossover (EPX-205) divides the signal before sending it to the equalizer and amplifiers through PPI DIN and Phoenix Gold RCA cables.  The crossover also provides control over the subwoofer crossover point and subwoofer volume.

Both components were flush-mounted in a custom fabricated steel bracket covered by an ABS plastic trim piece.

Polk Audio tweeters (MM 3000) reside in the forward corners of the doors, with grilles covered in matching gray Phoenix Gold grille cloth.  Polk audio passive crossovers divide up the signal to the door speakers.

Polk Audio 6.5" woofers (MM 6510) are installed in the doors' stock locations and are covered by the factory grilles, with foam baffles protecting them inside the doors.  A second pair of identical woofers are installed in sealed enclosures flush in the kickpanels (quite a task) and are covered by custom-fabricated grilles also finished in matching grille cloth.  With all the speaker grilles in place, the drivers are virtually invisible in the vehicle's interior.

(Shown with grilles removed)