How to get 14 volts

You might get a little over 14 if you are speeding down the highway, but if your going average speed down a road with your accesories running, or if your idling with nothing running then 13.8 is a good average voltage.

To add to what was said, with newer, upgraded alternators, they usually tend to not put out as much power idling as you'd think.  You usually have to get the car going to a decent RPM to get the power you paid for.

So, if you plan to be showing this stuff off to your buddies in the driveway, be sure to check out the amps this thing can put out at idle speeds, not your highway speeds.