My first Kougars had a ST 45 ring and ST 45 abc engines. They were built stock and flown off grass. In both cases the landing gear wood blocks wore into the foam wing cores and they developed a lot of play. I repaired each and sold them. The third Kougar I now fly has a Webra 50 Speed, wider ailerons, and I replaced the plastic turtle deck and cowling with balsa. we now have a asphalt runway so landing gear problem disappeared. I never reinforced any of the wings or fuselage. This Kougar is extremely fast, has a very fast roll rate, lands quite easily, and looks fabulous. It is now 4 yrs old with well over 200 or 300 flights but still looks great. If you reinforce anything, make sure the 1/4"-20 taped hard wood blocks that hold wing to the plane are well secured to the sides of the fuselage. Webra 50 turns a 11x6 MAS prop with 10% Cool Power at close to 13,500 rpm on a good day.