Superformance Alternator Problems

[E44i5]

I've always had a problem with my alternator and power with my car. It was never a big deal that bothered me too much, the car always ran ok, would usually start, the voltage gauge would only drop to around 12 volts unless I turned on the heat, lights or cooling fans. As long as I only turned on one of them the car was fine. I was told that it was the underdrive pulleys that where installed on my engine. Not to mention the battery that needed to be replaced. It now is a problem. I've just had a stereo installed, to say the least it is a loud, but now the alternator isn't worth crap. I've already got a brand new battery, it helped but it didn't solve my problem. I've looked into aftermarket alternators that make hi-amps at idle. Two problems arise, I can have one hand built ($850) which is not really what I want to do, or i can buy a aftermarket hi-amp unit. The problem with the aftermarket unit is that almost all of them are internally regulated, the superformnace has an external slectronic regulator. Is there anyway to change the wiring for an internal regulator, or is there a benifit to the external regulator, or is not even possible to change it? Any help in this matter would be greatly appreciated.
-E44i5