Power sources will provide current demanded by the load device or in the case of a direct short they will provide the maximum amperage they can until something burns open. I believe a high output alternator is simply ABLE to provide higher amperage than a standard output one. I don't know but they may run at a slightly higher voltage but this is controlled by the voltage regulator. Think of voltage and current in terms of a water source travelling through a hose. Voltage is the pressure and current is the volume of flow.
There's no 'I' in denial.