you can replace it with a turbo alternator but you may have to change the pulley if you have a serpentine belt...my turbo alt uses a v-belt.

YOu can increase the alt capacity by maybe 15% or so with an adjustable voltage regulator from ipdusa.com I wouldn't go much over 14.2 volts

Or you can send your alternator in an get it rewound/rebuilt for maybe 140-160 amps. I dunno what this would do for low rpm performance...you might drop output below 1000 engine rpm somewhat but it would pick up dramatically at 1000 engine rpm (alternator at 2500 or so depending on pulley ratios.). You'd have to do some research on the web and find the pages of various suppliers. try google on bosch alternator. I found an aftermarket supplier of GM alternators a few years ago and asked/emailed him a note asking if there was a GM alternator that was a form/fit to the B230FT engine. He matched the external measurements to a GM list and found nada but suggested I mail my Bosch alternator to them and they could rebuild it to 140 amps or so. I guess rewind the rotor and field coils to generate more juice.