i just put on my dc power 270 amp alt and now from idle all the way up to 3000 rpm it sits at 12.3. I have tested it with a damn and it matches my VM in my car. with stock alt I stayed around 14.4 until I turned my system up it would drop to the low 13 high 12 now it's dipping down to the 11s and idea what might be my problem?