I have a 2004 vw jetta and recently had 2 10" kickers and a 1,000 watt amp installed. I plan on adding more subs, new speakers and another hi watt amp in the future. But for now I would like to fix the dimming that occurs with all the lights in my car. I've found that the stock alternator puts out 90 amps. I've looked online and found 120 hi amp alternators. Is 120 enough to fix my problem AND enough to add on to in the future?