Stain, The alternator has the capacity to deliver up to 150 amps if needed for running the car or charging the battery. In cooler climates the 90/105 alternators will deliver all the power the car needs to operate fine but as the temperature goes up in the air and the alternator heats up from putting out current , the current delivery goes down. If you take it to a shop that has the proper current reading equiptment, you will see the current go down as it heats up. Is the 150 amp an overkill, yes in most cases. But I can build a new alternator with this kind of output for less money. Then if you add equiptment or want to have the assurance you have got the battery fully charged and are tired of seeing the voltage needle below 13 volts on all the short trips that are made, then the higher capacity helps. Like I said, they are tested at 2000 rpm, with a 100amp load. Turn on the air conditioner, lights and other equiptment and watch the needle go below 13 volts. If it doesn't come back up with higher RPM, then you maby get stranded sometimes because the battery isn't getting charged enough. John Hervey www.specialTauto.com