Cap's not only keep up the constant voltage to the amp, they also save your electrical system. One of the quickest way to kill either your battery, alternator or both is to have an alternator try to keep up with a high powered amp. Trust me I've killed them all in 10 years of mobile audio...

Pioneer DVH-P7000 DVD / MP3
Resonant Engineering 12" DVC XXX ( www.respl.com )
Hifonics BX1500D
StingPro 3.0 Farad Digital capacitor w/ dig. voltage readout
Boss Audio 0ga Wiring
Ported Enclosure tuned to 30hz
1500RMS X 1 @ 1 Ohm

BTW - you can get this cap off ebay for around $100 + shipping