1911
chupacabra
Yes, but you can definitely smoke your system with too many amps as well.
The great thing about an alternator (as opposed to a generator) is that it will only put out the actual amps needed or drawn by the stuff in the system, up to the rated amperage. The one thing that would be smoked in a 40 is the ammeter, assuming that any secondary wiring you added for a winch and etc. is up to the task. I have been running a 200-amp alternator for 11 years now, and it is great for my purposes. I did replace the ammeter in my instrument cluster with a voltmeter, and upgraded my battery, starter, alternator, and ground cables to much heavier gauge than stock.