I have a 2006 Ford Taurus SEL, and in my opinion, the lights are relatively weak. My high beams are fine by my standards just seem weak to me and that I need more power. The lenses aren‘t yellowed or anything, they are relatively clean and seem perfectly fine. I‘ve considered buying new bulbs such as the Sylvannia SilverStars but over the course of a little research, it seems to be hit or miss. I don‘t want to waste $40. Ive been thinking that it could be a power issue as well. Sometimes when I turn my music a little louder and I‘m running my lights, my lights will dim when I hit my brakes or when my speakers draw more power. Everything in my car is still factory based, nothing aftermarket. So if anyone has any tips on how to improve my lights, please let me know. It will all be greatly appreciated and thanks in advance.
The lights are probably just fine. The Silverstars supposedly give you brighter lights and go farther both in front and on the sides. The lights will naturally dim a little when you put a draw on the electrical system like from the brake lights or especially the stereo when it's loud. If you are worried about it then get your alternator tested at a garage or a major auto parts store. Everything you described is normal though.