I am pretty confident that there's no harm in having a 400 amp alternator. As long as everything else is good to go that just means you can have a higher amperage load (lights, winches, etc).Anyway, looked up a few possibilities for an upgrade… DC alternators in CA, expensive and a modest increase in amps, over stock…JS-alternators in SC, slightly more cost, but much more amps over stock…(is there a point that too much amps is too much?). And then the local parts stores with remfc and or same stock amps or slightly more at a cheaper price point? Hmmm ? What would U do?