my volt meter barely dips when i'm playin my music. which consists of 300 watt amp for highs and 1500 for my 2 12in subs. i also have a red top optima battery in the trunk. but whne i turn my AC on...in the day time (no headlights) the meter drops to just under 12volts. and sometimes i can tell the car gets sluggish. if i'm really beatting with the music, it goes down to 11.8 volts. if i turn the AC off it goes back up to 12.5 - 13 volts. i have stock alternator, should i get a 200 amp one?