I built my Tiger exactly as the instructions said for everything BUT, On the cowling I fiberglasses that area from the firewall forward, inside and out. I also painted the inside of the Fuel Tank Compartment with thined epoxy to seal this entire area. Which I think I may have coincidentally defeated the tail heavy characteristic of this plane during construction. I'm using a O.S. 61FX. I used some scrap plywood to make triangles to reinforce the plywood inserts that hold down the wing, as per the advice of this website. Last but not least I did NOT use the provided stock for the wing tips. I simply capped these off with 3/32 balsa and called it a day. I flew one of these kits that was "beefed up" Not too terribly heavey but there were some noticable wieght bearing additions made to this persons kit and it really discourged me when I checked out the performance. I carried on with mine and did my best to try and make the kit as absolutely lite as possible. What a HUGE difference. Make this kit as lite as you can. It's a real SLOW and GENTLE landing plane, so there is no need to beefe anything up. The Aerobatics are TRUELY sport like in that it will do all manuevers very well with some proactice. Pefect airplane for moving away from the trainer and into midly ADVANCED Aerobatics.