Well, I've got a couple more props to try, and a different muffler. Plan B is to put my YS63 in. I moved the CG back to 4.75" and it doesn't really get me anything.

Mine doesn't snap well. I'm trying hard not to bury it too deep with the elevator. It's more like a snap barrel roll.

One other thing. It sounds like a space ship! What's up with the thrumming sound?