My cousin found that out when he attached a small muffler to a Generator. they ended up buying one of those little Honda ones.
I've been looking at doing the same thing though because I have a small pressure washer similar to this one but without the wheels and long handle. It sits unused most of the time so I thought maybe I could make it easy to swap the pump for a pulley and leave the alternator on the front and justswap back and forth as needed.