So, I’ve collected a bunch of pieces I’m gonna assemble into a Pitts like airplane. I bought a set of Flat wings for a bargain and with a few mods will go with the fuse that Tom in Indy gave me the long deal on. A friend is helping with some of the mods and his airplane has the M6 but he swears the top wing is a modded version of the M6. I plywooded the leading edge 25 yrs ago but didn’t notice anything that indicated it was modified. His thinking is that it is “rounder” like the S has differing airfoils for stall characteristics. Has anyone seen or heard of this being done on flat wing? His was the only flat wing I’ve flown, so I don’t know if it performs like any others.