I have a system in my car. The last time I checked the volt meter built into the amp it read 12V but now (couple months later) its reading 14.4V. Is this normal or is this a problem? I have a capacitor that I am going to be connection probably tonight. Is there something wrong with my voltage?

You probably checked it once while the car was off, and once while it was running. I'm assuming the amp is hooked directly in line with your battery. When the car is running the battery will actually be between 13 and 14 (roughly)if the alternator is working properly