When your lights dim, it's more an installation problem. If you're running a big enough amplifier to dim your lights, you're asking for a fire. I've seen many a nice car burn from wiring that isn't up to snuff. Yes, installers use the big heavy gauge wires for the amplifier itself. The other wiring grounds some of the current and that's what catches fire. A higher output alternator may help but you need to upgrade the battery to a heavier one. The battery is a key part of your electrical system. Pardon the pun but it acts as a shock absorber for the alternator. You don't notice it, but the alternator puts out power in sharp pulses. There /s an internal diode that only lets the current out put go one way. Old style generators produced direct current. Alternators produce alternating current but automotive electrics require direct current. The diode makes the current into something your car can use.
If you can install a high amp battery for a diesel in your car along with a higher output alternator, it will help. If your entire trunk is full of the amplifier and speakers, you may need to learn to live with dim lights. All the cars you see at sound shows aren't meant to be daily drivers.
Honk if you love Jesus.
Text if you want to meet him.