I had posted about this a some months ago, but here goes again: The output from the inverter in watts is about 10X the amperage draw at 12 volts. to put out 2,000 watts will require 200 amps on the 12 volt input. A car battery will not provide this for more than a few minutes at best, so the alternator needs to be able to carry the bulk of the load. The limiting factors of alternator output are rotor RPM and drive torque. Unless You put a deticated drive pulley on the motor, You will have insufficient RPM and torque to get high amperage from ANY alternator. Alternators are usually rated at arround 6,000 shaft RPM, so with the engine running 1,500 rpm You need a pulley 4X larger on the engine than the one on the alternator to get rated output. For enough torque to properly drive a 150 amp alternator You will need doubble belts. Some companies have made "delivery truck" alternators that are designed for greater output at low RPM. These, if You can find one, are the better choice for a direct replacement using the stock drive setup.