Prop for Kyosho Spit with YS63
I use a 12 x 6 on a YS 53 in a Sig SE and it will fly the monocote offo of it. You probably will get the best performance increase with the 20/20 fuel which is recommeneded for the engine. However, as far as the props are concerned you will have to try a few different one to find the performance you want with any particular engine-airframe combination