Here's the deal... I have a 2012 Ford Fiesta, and I'm not sure what the alternator amperage is. All I know is that I have a Rockford Fosgate R1000-1D that puts out about 500 rms at 4 ohms and 1000 rms at 2 ohms. My subs right now have a total impedance of 4 ohms so its putting out slightly over 500. When I'm cruising down the highway with my music all the way up in 5th gear I get fairly profound headlight dimming during bass hits. I also have a 1 farand Rockford Fosgate Capacitor. I've been looking to upgrade to two 4 ohm subs so that would make my impedance 2 ohms overall and therefore putting out two times more power (1000 watts rms). I'm really worried about my car's electrical system. I haven't done the big three yet, but I'm not sure how much that would help, especially if I'm doubling the power to my amp and it dims the lights at where it's at now. Sometimes my system even cuts out due to voltage drop if I have my highbeams on and I'm listening to something with heavy bass. Also, I was looking into a 10 farand capacitor (Rockford Fosgate RFC10HB), but I'm not sure that would help much either seeing as how it would be pulling just as much power to it from the car to recharge itself. A high output alternator is not an option seeing as how my car is brand new, and no company has made one to fit my engine yet, that I know of. I'm just really not sure where to go or what to do from here. Any serious advice would be appreciated. Thanks in advance.