Aftermarket Alternators

I'm thinking about getting a alternator that puts out more amps. I openned my Jegs and Summit catalog and there are tons of alternators, mostly for GM and Ford. If anyone is running a aftermarket on there mazda what is it and where can i get it? How many amps does it put out and did it bolt in or did you make brackets? I imagine you gotta make brackets but if i have to do that then i should be able to buy any alternator.