Car: Toyota Yaris 2010 1.5L 4 cylinder engine. Subwoofer: 12in 1,200W Amp Batteries: a new 720CCA battery in my engine compartment, and a 300CCA battery in my trunk.
I have the stock alternator, radio, speakers, and no capacitor.
I've not been having issues with headlight dimming. The only issue has been that my subwoofer works at any time my headlights are not switched on. As soon as they are turned on, the sub words. As soon as I switch the headlights off, the sub works again.
I've been considering getting a 150 amp high output alternator and upgrading the power and ground wires with that alternator, but am uncertain if that would solve my issue.