And/or.. the instructions for each of those should state somewhere how much current they draw, so you could just add it up. The alternator puts out about 27 amps. One other thing you could do - since the winter gear probably draws the most - raise your idle speed up to about 1100-1200 rpm and see if that helps.. it works for me, but I don't have a GPS and I keep my hot pants on low.
To answer your original question, I have yet to see an upgrade for our alternators anywhere. If my poor man's freak design ever gets finished, I'm thinking about installing dual batteries..... just to "spearmint".
