ORIGINAL: TimBle
You're lucky, I know of owners who had the firewall pull out while the engine was at full tilt. They have holes in the garage brickwork to prove it.
Mine firewall fell out when I dropped the fuse off the workbench. Stripped the servo's geartrain.
Id also check the wing attachment points and all the bulkheads...
Good advice. When I put it together I put an extra 1/8" ply on the inside of the wing bolt firewall. That all still looks good. I have brass tubing over my wing dowels as well to keep them from wearing out.