I HAVE BUILT 4 COBRAS.. THEY ARE FAST AS IS.. OS .61SF,,11.7 PROP,PIPE .. REAL FAST!! I THINK THE STOCK WING WORKS SUPER,,LANDS VERY SLOW.. RETRACTS ,,THIN TRAILING EDGES,TIGHT WING TO FUSE JOINT,,,WILL HELP MORE THAN LEADING EDGE SHAPE.. HAVE FUN--------- RD