Last year I put in a new head unit and 4 new kicker 6" speakers, 50 watts RMS Each. They certinaly sound much better than my factory tape deck and speakers, lol. This year I want to put in an amplifier to help boost performance, and possibly a subwoofer. The question I have is; do I need a more powerful alternator at some point? should I get a 5 channel or a 4 and a seperate 1 for the sub woofer? I know a little about audio, but not a ton.