Your going to be needing a good hearing aid soon to go with that sub and car audio system. There's a good reason people who work around jet engines at air ports wear hearing protection, you know. The decibles in a closed car audio system can equal and exceed those found around a jet engine.
When you start noticing you need to turn it up more and more and your ears ring constantly, you have finally achieved car audio nirvana and reached permanent hearing damage that is not reversible.
I sure hope when you are cranking it enough to dim the car lights, you aren't in the car, but nearby listening to it. Which is why custom show cars with killer sound systems have remote controls on the audio systems. You won't catch them in the car cranking it, they aren't that stupid.
There's a number of ways to fix unstable or low voltage, including bypassing the cars electrical system completely, and running it off separate batteries that are charged by the alternator. But to do that, you may also need a sizable alternator upgrade, and this may also effect fuel economy and performance somewhat, as well. And remember too, that low voltage can be just as stressful on a struggling electrical system as over voltage can be.
And when, not IF, it shorts out your cars electrical system or melts the electronic control circuits that operates your car, don't say you weren't warned, and that will really cost you a bundle to fix.
