A friend of mine built this kit (not the ARF) back in the 90's. The thing was way overbuilt and had way too much heavy plywood in it. It flew like the proverbial lead-sled. If you ever wanted to see what a high speed stall looked like, this was the plane to do it with. With it being so overbuilt, I'm sure that it could be lightened a whole lot without sacrificing any strength. You might even consider using 1/4 square balsa sticks to build up the sides, using the heavy ply sides as a template (Look at the SIG Kadets to see what I mean). A couple of 1/8 sheet balsa doublers at critical areas and you are in business. Good luck with it.

Cheers!

Jollidude