Here is a place that seems to have pretty good prices. Alternators (http://www.alternatorparts.com/) I bookmarked it from someone elses post a while back. There are a number of different high output alternators on the site so look around. I believe that Havasu Hangin said a while back that he wouldnt go over 150 amps because you can only charge so fast or burn up the batteries.. and I believe he is the internet wire jockey.