I see a few differences in your plane. My landing gear is regular straight 5/32 rod. Yours has the loop. Also mine has 2 plywood wing reinforcement pieces that glue over the holes for the nylon wing bolts. I didn't see those on yours. I didn't actually use the strip of monocote they include to cover the wing joint. I used the 2-ton epoxy that cures in a couple of hours so I got a good bond that looks good without the tape. With the FS-91 it balanced perfectly without any added weight. Receiver pack still is mounted to the side of the engine mounting block out front.

The 3-blade and larger spinner probably also help.