I switched to a 130 amp alternator about 9 months ago, using a custom made alternator that I got on eBay. (The custom part is that it was in a smaller case than the usual 130 Ford alternator, so that it fit onto the alternator bracket without modification.) An odd thing happened after about 6 months. The alternator stopped charging. Since it was not a simple matter of collecting on the warranty (which was only 90 days) or getting another one at the local store, I let the car sit for a while & finally took it to an alternator rebuilder. I was surprised when they came back & said that the alternator was charging fine and they could find nothing wrong. To make a long story short, it turned out there was some kind of failure on the little wiring harness that the alternator seller had provided to make the alternator "self-exciting". I wired in the connectors from a 1993 Taurus, so that the alternator got it's excitation current from the ignition switch & the thing started charging again.

If I had it to do over, I would have bought a 130 amp alternator from a 93 - 95 Taurus at the junk yard and modified the mounting bracket to accept the larger case, as shown at these websites:
http://www.mustangcentral.net/tech/alternator.html
http://ylobronc.users.superford.org/alt2.html