i put the light one, with mufler, prop mount and propnut on the scale, tare it, then put the heave one on the scale, and it tells me the difference, which was on the 63 vs the 91 3-5 oz, depending on the long or short hattori muffler.
i have never trusted direct weight comparasons, especially if the weights come from the mfgr/seller

and yeah, it is great with a 16x4 or 16x5 prop and rpm restricted to 11,000