Your engine is too new and tight for the 15x10 just yet.

Get some run time on it with a 15x8 and after it loosens up go ahead and up the prop size.

I run the APC 15x10 on this engine in my TF F4U , a KMP Critical Mass, and a Skyshark ME109G6. They all run strong and fast.

The Critical Mass may actually need more prop. I'm still experimenting on that one.