RE: How does big two stroke engine sounds like ?
Best sounding engine I own (and that includes OS and Saito 4-strokes from .52 to 1.80 displacement) is the MOKI 2.1 two-stroker.
Like Ed Cregger said above, it has a deep bass, real throaty sound, which to my ear is very pleasing - more so that the sound of my big Saitos which actually have quite a bark IMO.