RE: GP Shoestring 1/4 scale
What's your intentions with the Shoestring, everyday sport flying or racing. I flew mine with an very old OS 61 FS. Plenty of power for everyday flying. Put over 200 flights on the plane and engine, before I sold it and purchased another one. Just add a little wood in the landing gear area and you will be set to go. OBTW, I had to use 2 ounces of weight in the tail to get mine to balance with teh OS61. Therefore, my recommendation is the Tower Hobbies engine.