Do you have a stereo system blackened? Are you running mainly at night or during the day?
I agree with both though. Blackened is right something is not doing its job all the way unless you are trying to run something like a big stereo that draws a ton of power.
Also I would always recommend running a 3g alt. There is a reason it went standard affair on 94+ mustangs. The stock one is wayyyyy too weak. About as adequate as stock brakes.