Saitos do not have this flat spot, their throttle response is very linear unless not set up correctly. If your TT has a two needle carb, it should not have a flat spot either. If your needles are set correctly you may have a fuel or a glow plug problem. My Enya .46 is the only four stroke I have that had a flat spot, I blamed it on the air bleed carb but found out I was running too large a prop.