I did the same thing as Shaggy48. I glued a piece of ply between the cheeks & also used them to put a couple of oz of weight on it. That put the weight just behind the prop. I personally don't like the idea of puuting extra weight & stress on the engine with a weighted spinner. I played with it for a while, it would've taken 6 ozs. if I placed the weight on the firewall. The weights are easy to get to later if needed to change the CG.