OK... I'm going to show my lack of engine knowledge here...

Was/is there an OS .91 four stroke that ISN'T a surpass??? Just kind of curious, sometimes I hear different combinations of the terms...

Now... for a slightly different topic, would the Biplane Police throw me in jail for putting a 3-blade prop on Hog Bipe????

And if a 3-blade is acceptable.. about what size prop would one bolt onto the front of an OS .91 FS (surpass )...

Just speaking hypothetically of course...