STG. I just did another test tonight. About 86 degrees. A little hotter tonight than when I did my last tests. But tongiht I got about 9400 RPM with the 16x6 (Peak about 9550) and 12lbs 8ozs thrust. With the 16.5 x 5W I could get 8800RPM and only about 12lbs 5 ozs thrust. And that was as high as I could get the speed. She won't do any more, not at my elevation. So for me the 16x6 prop is better.
If you want to try it I will send you the prop at no charge, since I won't be using it. I don't know if it is a freak couple of props or not but it doesn't work for me. Can't speak for someone at a lower elevation. My engine really heated up also.
If you want to try it, PM me with an address.
Thanks
Barry