Battery

I have a Memphis PR 300.2 amp pushing 2 10 inch alpine type s subs. The gain is at half and the bass boost is at 3/4. My problem is when im at a stoplight, my battery light comes on during the deep bass notes. The battery is almost 6 years old anyway so i was thinking of getting an optima yellow top. Do you think this would solve the problem or do you think it would drain the battery over time? My alternator is the stock 60 amp that came with my car. Do you think a new battery will do the trick or do you have other remedies? thanks.